It's not a question of "important".
For all the talk about how dreadful Jeremy Corbyn is, most of that has been coming from the Labour Party itself. Starmer has purged Corbyn and anything remotely connected with him with a zeal that would have made Stalin proud. He has been comprehensively unpersoned, and derided as responsible for everything that was wrong with Labour through two electoral cycles.
Given that the population of the UK, and therefore, the number of total electorate has risen, to demonise Corbyn and then return fewer votes than Corbyn himself managed several years beforehand would be hilariously ironic. Happy accident that the Tory vote has collapsed utterly and left the door wide open for a Labour majority, but it changes nothing about the fact that Starmer will have attracted fewer votes than Corbyn, and would therefore be inarguably less popular than a man derided as completely unelectable. 😆