Hmmmm. Some cherry-picking of brief, unrepresentative periods out of their careers to make a point?
IIRC Jess Philips had a managerial role at a women's age refuge, hardly an "ordinary job".
Not exactly working class or without political connections and ambition either:
"Brought up in the left-wing belief system, her early ambition was to become a Prime Minister. At the age of fourteen, she received her Labour Party membership card and at sixteen started taking part in election campaign, marching beside her parents in different rallies."
https://www.thefamouspeople.com/profiles/jess-phillips-50443.php
"Jessica Rose Phillips was born on 9 October 1981 in Birmingham, West Midlands.The youngest of four children, Phillips is the daughter of Stewart Trainor, a teacher, and Jean Trainor (née Mackay), an NHS administrator who rose to become deputy chief executive of the NHS Confederation and chair of South Birmingham Mental Health Trust.
They were politically active: "Growing up with my father was like growing up with Jeremy Corbyn", she told Rachel Cooke of The Observer in March 2016. Phillips went to King Edward VI Camp Hill School for Girls, a local grammar school. Her childhood ambition was to become Prime Minister.
Phillips studied economic and social history and social policy at the University of Leeds from 2000 to 2003. She has said she marched in protest against the Iraq War. From 2011 to 2013, she studied for a postgraduate diploma in public sector management at the University of Birmingham.
Phillips worked for a period for her parents at their company, Healthlinks Event Management Services. From 2010 onwards, Phillips worked for the Women's Aid Federation of England as a business development manager, responsible for managing refuges for victims of domestic abuse in Sandwell in the West Midlands"
"In the 2012 local elections, she was elected as a Labour councillor for the Longbridge ward, taking the seat from the Conservatives."
(Very commendable but not a patch on Duffield's success in taking the Canterbury Parliamentary seat, which had been held by the Tories since it was established in 1918.)
"She was then appointed as the victims' champion at Birmingham City Council, lobbying police and criminal justice organisations on behalf of victims. She also served on the West Midlands Police and Crime Panel."
"Phillips was selected from an all-women shortlist to contest Birmingham Yardley in June 2013, which was then represented by John Hemming of the Liberal Democrats. In the 2015 general election, with an 11.7% swing away from the Liberal Democrats, Phillips was elected as a Member of Parliament (MP), receiving 17,129 votes (41.6%) and achieving a 6,595-vote majority (16.0%) over her closest rival."
(Jess was promoted to the Shadow Cabinet in 2020. She had several well-publicised disagreements with Party Leadership and threatened to resign from the Labour Party and stand as an Independent - she did leave the Party for a while before she entered Parliament. Jess also keeps busy outside Parliament)
"Since 2019, Phillips has received the second highest income on top of her MP’s salary amongst Labour Party MPs"
(Left wing, professional parents in high level jobs who also ran a business. University educated to post grad level with a Management qualification. Worked for her parent's company and then went into management in the voluntary sector. Two years later, entered local politics as an elected Labour Party councillor and subsequently achieved appointment to other very responsible positions in local politics.)
https://en.wikipedia.org/wiki/Jess_Phillips
Catherine West "was born on 14 September 1966 in Mansfield, Australia, one of four children to Janet (née Conti) and Roderick West AM. Her parents were both teachers and her father was Headmaster of Trinity Grammar School in Sydney for 21 years. She is the great-great niece of actress Italia Conti. She grew up in Sydney and was privately educated at Meriden and Ravenswood.
West studied modern languages and social work at the University of Sydney. While studying there, she met her future husband Colin Sutherland. They lived together in Darwin, Northern Territory where she worked as a social worker in a refuge for survivors of childhood sexual abuse. West and Sutherland moved to the United Kingdom in 1998 when he gained a job at the London School of Hygiene & Tropical Medicine. She then gained a master's degree in Chinese Studies from the School of Oriental and African Studies, University of London."
West joined the Labour Party in 1998 and became a caseworker for MP David Lammy two years later. From 2 May 2002 to 22 May 2014, West was a member of the Islington London Borough Council representing the Tollington Ward. She was the leader of the council's Labour Party group from 2004 to 10 October 2013 and Council Leader from 6 May 2010 to 10 October 2013. She resigned as councillor in order to contest the 2015 general election.
She was elected Member of Parliament (MP) for Hornsey and Wood Green in the 2015 general election.
Following the election of Jeremy Corbyn as Leader of the Labour Party, whose campaign she supported, West was promoted to the Official Opposition Frontbench as a Shadow Foreign Office Minister.
(Privately educated, professional parents, university educated, rapid ascent in the Labour Party after only two years membership. Stood for a safe seat and was promoted to the Shadow Cabinet four months after she was elected.)
https://en.wikipedia.org/wiki/Catherine_West
Louise Haigh "grew up on Abbeydale Road, Sheffield, and now lives in Norfolk Park, Sheffield. She was educated at Sheffield High School, an independent school. She then studied government and economics at the London School of Economics but did not complete the course, and opted to study politics at the University of Nottingham. Her grandfather and uncle were trade union officials.
After graduating, Haigh worked for the local council youth service from 2006 to 2008. She then began working in Parliament, where she was the co-ordinator of the all party parliamentary group on international corporate responsibility. During this time, she was also a Unite shop steward and volunteered as a special constable in the Metropolitan Special Constabulary from 2009 to 2011.
From 2012, Haigh worked for Aviva as public policy manager, responsible for corporate governance and responsible investment policy."
"Haigh was selected to stand for the Labour Party in Sheffield Heeley in May 2014. She was first elected to Parliament at the May 2015 general election and re-elected in June 2017 and December 2019."
"In September 2015, Haigh was appointed Shadow Minister for Civil Service and Digital Reform. The role, newly expanded under Jeremy Corbyn, covers the Government's digital strategy, the Freedom of Information Act, data security and privacy."
(Privately educated, trade union family, studied politics at University, two years working for the LA youth service, then party apparatchik working in Parliament followed by a high-level management job. Promoted to Shadow Cabinet four months after being elected to Parliament.)
https://en.wikipedia.org/wiki/Louise_Haigh
Angela Rayner is closest to Rosie Duffield in terms of upbringing and personal experience. However, Rayner benefitted politically from a career in the trade union movement. This gave her many advantages, perhaps including her meteoric rise to the Shadow Cabinet less than a year after being elected? A bit of a slow-coach though compared to Catherine West and Louise Haigh's mere four months before their promotions to the Shadow Cabinet.
"Rayner was born and raised in Stockport, where she attended the state secondary Avondale School. She left school aged 16 whilst pregnant and without any qualifications. She later trained in social care at Stockport College and worked for the local council as a care worker. She eventually became a trade union representative within Unison, during which time she joined the Labour Party. Selected to contest Ashton‑under‑Lyne in 2014 and elected for the seat at the 2015 general election, she was appointed Shadow Minister for Pensions by Jeremy Corbyn in January 2016.
Rayner was promoted in July 2016 to the Shadow Cabinet as Shadow Secretary of State for Education and Shadow Minister for Women and Equalities."
https://en.wikipedia.org/wiki/Angela_Rayner
"Rosemary Clare Duffield was born on 1 July 1971 in Norwich, Norfolk, England. and later moved to South East London where her father worked as an anti-terrorism police officer. She left school at the age of 16 and completed an administration apprenticeship at Guy's Hospital. She then attended a further education college. She moved to Canterbury in 1998 and worked as a primary school teaching assistant in various schools, before becoming briefly a political satire writer.
In 2015, Duffield stood in the St Stephen's ward of Canterbury City Council where both seats were won by the Conservatives.
Duffield was elected to parliament in the 2017 general election with a majority of 187, defeating the incumbent Conservative Member of Parliament (MP) Julian Brazier. Brazier had been its MP since 1987 and the constituency had been represented by a Conservative since its creation in 1918.
On her election, she was appointed Parliamentary Private Secretary (PPS) to Dawn Butler, the Shadow Secretary of State for Women and Equalities. On 13 June 2018, Duffield was one of six MPs to resign from the Opposition frontbench to vote in favour of remaining in the single market by joining the European Economic Area, as the party had instructed its MPs to abstain. She has been a member of the Environment, Food and Rural Affairs Select Committee since March 2020 and was previously a member of the Work and Pensions Select Committee between June 2018 and November 2019 and the Women and Equalities Committee between September 2017 and June 2018 and March and May 2020."
Angela Rayner, Catherine West, Jess Philips and Lou Haigh do not seem to be best examples to refute Duffield's satirically-expressed comments about her own personal and political background, and subsequent time in office, compared with other Labour Party MPs new to Parliament:
"As somebody who wandered into this Hogwartian world from an ordinary job, I am a stranger to the dark art of “spin”. I do not come from a long and distinguished line of former wizards working at the Ministry of Magic, I did not get a scholarship here because my friends or family saved me a seat and I did not go to kindergarten with anyone who works in the Headmaster’s office.
So I watch with amusement at those who slotted into the very safest Labour seats — where they replaced disgraced, retiring or fed-up former colleagues — get promoted to the shadow frontbench after a mere handful of appearances in the chamber (of secrets) and without so much as attending even the first lesson in How to Communicate Well With Muggle Voters. Hardly the most obvious possessors of sparkling charisma or subject specialism, they are tweeting their gratitude before even the first chair is installed in their new offices. So what is their secret? What is the magic needed to proceed so effortlessly at such rapid speed?"
https://unherd.com/2023/09/the-dark-art-of-toadying-to-starmer/