They don’t address that at all. They acknowledge the ankle wings and just say that he’s different from the rest of his people. (Second instance of the “M-word” in the MCU.) Aside from that, he has ankle wings that make him fly, and the audience has either bought into enough of the MCU BS to roll with it or not.
As for the rest that anchors him into the world, they did a good job of giving him an origin that makes him a sympathetic villain like they did Killmonger. I don’t like that they changed the pronunciation of his name, but they did it for a reason. What they did was something that worked for me.
The director wanted Namor, and he wanted him in as soon as the post-credits scene from the first film. Based on what he did with the character, you can see why the character was so appealing. Plus there’s history. Namor was one of the first characters Marvel published, before they became Marvel. I’m sure someone working there is annoyed that they managed to get Howard the Duck into the MCU before Namor.
