JazzG Corbyn bought a complete shit show to Labour but did the left wing activists who want him in own up that they nearly killed off the party
He got 40% in 2017 then 32% in 2019. Vote share is a complex matter but there's little doubt Corbyn was beaten by a far more effective opponent than Starmer (33.7%) managed to get past in Sunak.
The argument Corbyn was unelectable is complex but if he was, I'd say it was down to lies and fear.
The 40% of the vote Corbyn won in 2017 was one of the best results Labour's achieved. Corbyn became very unpopular (in the face of a continual thrashing from the press), and was too easily fucked over by rats in his own ranks. But the rest of the line about him is mostly received wisdom.
As for the "left wing activism" Corbyn's platform was boring, orthodox Keynesian social democracy, that is, prosocial policy that, subject to the continual terrorism of capital of course, is intended to make society incrementally better, stimulates demand, and protects people from misery.
All it would take is for the same piece of shit journalists who puff Farage up to back a social democrat with their sabre-rattling editorials, and the public would love the idea.
This was just as much the case when Corbyn was leader, and the UK was still bleeding heavily from the extraordinary economic violence of Cameron and Osborne's austerity project, conducted against the recommendations of every economist.
Instead the press corps gave us "Jeremy Corbyn the antisemitic friend of Hamas", a take that's aged like genocidal milk.