This is a weird example to prove your point. There are absolutely no current historians seriously claiming Rome was founded by Romulus and Remus, and even contemporary Romans didn't really believe the story (sort of: Roman beliefs about their own history were a delicate balance of keeping a few different, mutually contradictory, ideas in mind simultaneously, but it's safe to say that a lot of them didn't think the story of Romulus and Remus was literally true).