I'll try and check my biases, but - to be upfront - I'm on the left.
Although your posts sound reasonable (and are, in parts), I don't think I agree them in their entirety.
In a US context, I don't think there really has been much of a swing to the left at any stage. Looking at the 2000s, we had George W. Bush (traditional right wing conservative), Barack Obama (a centrist Democrat), Trump (radical right wing populist), Biden (centrist Democrat), Trump again (more radicalized than the first time).
While I hate a lot of Trumpian politics - if he wins and election, then he gets to set and carry out his agenda - that's how a democracy should work. What makes Trump, and those around him terrifying is that they do not respect the democratic process. He and his supporters (including Charlie Kirk) embraced election denialism and tried to overthrow the 2020 election results. Democracy held - barely - as certain key persons in his first administration put democracy above winning. This time, all of those democracy-safeguarders have been sidelined, and we only have the election deniers left.
Election denialism seems to have become mainstream on the Republican side, and isn't an fringe position. I would, sadly, be very surprised if we see free and fair elections in the US again in the foreseeable future. Denying democracy is likely the most extreme position you can take in a democracy!
In the UK, there was Blair and Brown's Labour (a very centrist Lab government), a string of Conservatives (some moderate, some further to the right, no extremists of the MAGA sort) and now a very centrist Labour government.
The only leftward-swing has been specific to the transgender issue. Certainly, there's a fair amount of hostility at a grass roots level, but I do think it worth bearing in mind that, at a government policy level in the UK, it hasn't really developed in a partisan manner.
And, as I've mentioned a few times, political violence (particularly killings) in the US is almost always an extreme-right issue. It should still be condemned on those rare occasions where the extreme left engage in it, but I don't think they should be equivocated, given the massive disparity in frequency. E.g., I think most people would accept that male violence is a problem, and that pointing to the fact that sometimes women also commit violence is a lame defence, given the disparity in rates. The Right/Left split in politically motivated murders (around 95% to 5%) is actually more pronounced than the Male/Female split for violence and murders.
Things arent as severe in the UK, and I acknowledge that there are many, many inflammatory, uncompromising dickheads on social media, on the left and right. In the US, though, the problem is very much right wing extremism, which Kirk indulged in, and that should be recognized (although I do agree, that doesnt necessarily mean talking in absolutes).