It's ironic because inhumans, eternals, and Atlanteans are the only species to hide, but always exist, whereas mutants started to appear over the years. I know Apocalypse and Selene are billions of years old, but modern mutants are different in that they're modern. But mutants will probably borrow some traits from the other species, especially since they have or will appear in visual media.
spoilers:end of spoilers
I think eternals are being retconned in the MCU as aliens as opposed to experiments by the Celestials.