Earlier quoted context omitted.
you say that like undermining Corbyn is an objectively bad thing. He's an extremely divisive element of the current Labour party and the primary reason why I (and I consider myself a liberal first and foremost) cannot support the current Labour leadership. Labour's always been a mix of liberals and socialists but in my opinion Corbyn is too far to the latter to ever unify the party behind his ideas.
There are more Labour members supporting Corbyn than there were Labour members total before Corbyn became leader. Labour will never be unified as long as there is first past the post in the UK, and currently at least the left of the party dominates the membership. Any challenger to Corbyn at this point would depend on the support of the left of the party even more than during the last challenge.
And of course Corbyn is completely out of whack with his membership, being pro-Brexit while the party is heavily for Remain. Remain effectively doesn't have democratic representation, and nor does the business-focused middle ground.