Biden won for all sorts of reasons. For not being too threatening and, especially, not being Trump, sure. But he also had ideas of what he wanted to do and proposed to do. And he took the Democratic left and Black caucuses with him, who were both very instrumental in getting the vote out in key states.
If comparisons are to be made, I'd say Biden was Blair. Whereas:
Starmer is not Johnson. But he's only not threatening to the status quo. He shits on the Labour left, doesn't really give a fuck about racism, disbanded grassroots organizing, has no ideas whatsoever, nor it seems any integrity. Johnson's blatant lying comes across as more honest than Starmer's bland weathervane pronouncements.
Rubbish at politics is an understatement.