This may seem problematic as an idea but I think black panther 2 pulled it off in a respectful and interesting way.
Namor (king of Atlantis) has always been a big part in marvel comics, being the first mutant. But the way he was portrayed in the movie gave him an indigenous history that made him and Atlantis as a whole a lot more interesting than he’s ever been in the comics.
Ah yeah you’re right, I think Namor was at one point the first mutant in the original x-men comics but now there is Apocalypse and a few other mutants that came before him.