Well, to Doombot, I am not saying that any of those; Inhumans, Eternals, et al, are determinants of Atlantean culture, tech, evolution, but that given the vast, vast, VAST amount of time
there clearly was intercourse and intra species contact. No, I'm not saying that some great ancestor of the Inhumans had anything to do with "Atlantis".
It was others on this list who have teased the idea of Neptune being somehow an ancestor, so I just ran with that.
I'm not asking for Inhumans of varying sorts to be integrated into current Namor stories either. But those ones with Triton in the '60s were rather cool and I wouldn't mind them teaming up again.
But I do think that someone using magic or tech to transform any amount of air breathers to water breathers a little hard to take too. Wouldn't they have been easier able to escape the island/continent with those resources? Again the hand of Eternals or Celestials seems to be involved possibly.
So... there has to be another story here. I can't believe that somehow they just transformed at once, without big mojo happening.
I just don't find it reasonable to assume that these varying groups of underwater/abied peoples did not meet and exchange over thousands of years.
But clearly Marvel has indicated that Atlantis to some degree is derived from the previous Eternals/Celestials stuff. Heck, even Agatha Harkness has been indicated to be an ancient Atlantean - now that is a concept I am not supportive of at all.