The problem with this accuont, reasonable though it seems, is the lazy, ideological thinking and left/right compartmentalism that consistently seems to be driving this discussion. (Not suggesting that you are guilty of this, BTW, it's merely the state of the prevailing political winds).
The left/right divide as I once understood it, pivoting around economics, a fairer and more even distribution of wealth, adequate recompense for workers, pro-union stance, etc., no longer exists. It seems to have little left to do with this at all, but in the past 20 years has seen a move from fairer economics to 'progressive' individual rights as opposed to the rights of the collective. Note 'rights': not wellbeing or responsibility. Vote Labour, vote Tory, these days you get the same.
Those masquerading as the progressive left are now extremist MRAs, TRAs - the old domain of the slightly further than right-of-centre. Islam was never seen on the left post 9/11 - society was rife with Islamophobia which was equated with conservative religion and associated terrorism. Look at the total about-face in 20 years - now Islam/Palestine is viewed as 'left' whilst Judaism, at the ultimate butt off far-right hatred in WWII, is now viewed as occupying the right itself. I'm happy to consider other perspectives on that topic, but the thinking to my mind seems no more complex than that. The 'left' follow what's no longer left on pain of being branded 'right'; 'far right' at that, and what brands itself as progressive is quite often its own ugly, regressive opposite.
I can't pretend to understand the full nuances of the Israel/Palestine conflict. It's too ancient, too complex and too nuanced - and I'm thinking back to a day when Yasser Arafat was constantly in the news, the PLO had split off into the ANO, a serious effort was made at a compromise solution. Then Rabin was assassinated, after which the whole region became a simmering pot of resentment threatening to overflow at any moment.
I visited Jerusalem and the West Bank in around 2009. I've seen the mess first-hand. It only surprised me that it's taken this long for it to manifest. There is no 'siding' with Israel or Palestine. You're absolutely right that anti-semitism in the UK has reached a frightening epidemic, that the Hamas attack was racist hatred and terrorism, and that Israel has to defend its citizens. By the same token the 'open prison' thing re. the West Bank is often toted as a racist media stereotype. Open prison is exactly what it is. I've been there. I've seen it. I've seen how broken the Palestinian people were. I've also seen how they live within Israel itself - that isn't equality, they occupy the most impoverished reasons and have fewer opportunities. I also believe Netanyahu is orchestrating an unsanctioned, morally dubious, illegal land-grab and starving Palestinians. At present, do I believe that each side simply wants to wipe the other off the map, for which there's no other word for it but genocide? Yes, and one side has more resources than the other to bring that result about. There are also problems with the surrounding Muslim nations' support - or lack thereof - for the Palestinian people. Is a two-state solution even remotely possible? Probably not. We've seen how attempts at that panned out in the past.
It's an ugly, bloody, racist, horrible stalemate with no end in sight - as to whether that suits the political purposes of someone somewhere, that is another issue. But the ones who receive my full sympathies are the innocent citizens on both sides, who are in no way culpable for the actions of their defence leagues, insurgents and terrorists but are as always the first to suffer.