In addition to what @Evilphd666@hexbear.net said, it's worth mentioning that when he was the leader of the Labour party, it was extremely active with the membership. It grew to roughly ~600,000 members, the largest political party in Europe. Their policies were things like nationalising industries, forcing companies to have employee representatives on the boards of directors, and other socialist-leaning things.

But, since the core of Western countries is build on anti-communism, the ruling class could not tolerate that. Corbyn was far too generous and refused to purge the reactionary elements from within Labour, and when he lost the federal election (in no small part due to sabotage from within his own party as well as the baseless smear campaign against him), Kier Starmer - a man who believes in nothing - took over, and then Corbyn was himself purged along with the rest of the left-wing elements within the party.