I think people are mixing up copyright up with what Sony does with Spider-Man due to licensing terms. Like not only does copyright last damn near forever, you don’t need to keep releasing stuff to renew it and it doesn’t just go away because you aren’t using it.

There’s also a lot of confusion with trademarks. People will often defend big corporations threatening fan art because they “have to defend it or lose their copyright”, which is a trademark thing and not copyright.