Feel like my shyness holds me back at work

[Yadayadayadayada]

I'm pretty shy, quiet and introverted. It's something I've always struggled with in a working environment, if it's just me and one other person I do make conversation (though I run out of things to say) but if it's group I struggle.
I also find working with the same people all day every day incredibly draining.

I was in a supply TA role which was supposed to be until Christmas, working with the same 3 staff members in a classroom every single day.
They were of a similar age and a lot older, and I just found it draining to have to be around them constantly.

I could get some time alone on my lunch break, but otherwise no. I had nothing against them at all (though I did hear one slagging me off at one point) and we did make some conversation but I struggled.

I know this will be the case in other jobs though. There aren't really any jobs in which you don't have to talk to other people socially and spend a lot of time with them whether you like it or not.

I'm taking steps to improve my shyness, I feel embarrassed that I'm still the same in my 30s.
I don't want it to hold me back at work.
Does anyone else feel like this? Or managed to overcome it?

I have been considering a WFH job as well in order to deal with this

I think a WFH job is the way to go! I’m a teacher and have always thought I was just a bit of an introvert so my job didn’t particularly suit my personality that well. I’ve kind of forced myself to keep on pushing through it for so many years but eventually forcing myself to do it has broken me and I’ve ended up so anxious. I think the criticism/feedback you get as a teacher from management as well as parents, can really wear down your self confidence even if you don’t start off as shy. I joined a Facebook group called exit the classroom and thrive and it was only then that my life changed. I’d lived with all of these problems spinning round and round my head, never saying anything about any of it. I ended up on medication for my anxiety, particularly socially. I was just over thinking everything and it started affecting me outside of work too.

I realised when I joined that Facebook group (with almost 100k members now) that it wasn’t just me and I wasn’t so ‘weird’ or alone for feeling the way I do about my work. I’ve set up a business from home and realised I can make money that way, while not hating every second of it. I don’t dread it beforehand either! I just need to exit the classroom permanently now!

I also find working with the same people all day every day incredibly draining.

is this shyness?

Yabu, because there are zillions of jobs that don't need as much social interaction as a TA. There are also many jobs that don't need you to be in an office 5 days a week. Try looking for an admin job in a non-private sector, e.g. higher education, a charity, local government.