This isn't about Corbyn. He's a scapegoat for the people who set up an inadequate system to deal with anti-Semitism,then tried to weaponize it to damage the leader.
Instead, the 'centrists' of the party decided to make a fight of it. You will recall they started tweeting their resignations and refusal to serves during his victory speech. No "Well, let's see where he's going with this" - just straight in with the attempts to sabotage his leadership, from the get-go. Then there was the conspiring, the planned rebellion before the referendum, the Chicken Coup, the second leadership contest, the deliberate breaking of the discipline system with the intention of making the party look anti-Semitic and so on, all sauced with briefings and leaking and so on, which the rightwing media lapped up and which the Labour 'centrists' were too dim-witted to think 'why?'
So instead of May trundling along with the majority she inherited from Cameron until 2020 and suffering the same fate as John Major, we had the 'blood in the water' election intended to finish Labour off, which instead broke May's government. Then suddenly Corbyn looked potentially electable - so the campaign intensified, culminating in the 2019 election and the election of a thumping Conservative majority.
That's all down to the 'centrists' and their dim-witted 'grown up' politics. I hope they are pleased with what they achieved.
Though I suspect they actually are - leftists will look at how Corbyn was monstered and think twice about standing for the leadership, even though they know they will be in with a good shout. Because who would want to go through what Corbyn was put through, and is still being put through, by the right wing media and their enablers in the Labour Party?