Too much of the so-called left allowed themselves to be diverted down the virtue-signalling id politics/woke path and failed to get to grips with the reality of power. Naive like Corbyn.
It's perfectly valid to castigate the 'left' for naivety, cowardice etc.
But, given the existential threats we face, it's the responsibility of all of us. We can't keep scapegoating Corbyn, the left for ever.
When it comes to, eg, Ukraine, it's noticeable that it's part of the right that's more critical of the war party.
There's only one thing to learn from the failure of the Corbyn project (and the return to business as usual with Starmer). It is impossible to change the system from within the system.
It's even more mad to go down that conventional path given the time-frame set by the existential threats we face.