We are having an interesting discussion on the historicity of legendary Atlantis on the new Homeschool History list. My belief is that the Atlantis legend is probably based in historical reality. Most myths and legends from various cultures can be traced back to a historical reality, although the myth itself can be greatly exaggerated.
The gist of the Atlantis myth is that a great advanced civilization was overwhelmed by a flood and lost. That scenario sounds familiar.
The pre-Flood civilization could have been very advanced, we don’t know, the Bible doesn’t say. But if we discard what we have been taught about
grunting cavemen dragging their knuckles on the ground (a scenario which has no corroboration in history, myth, or legend), we can conclude that pre-Flood humans were very intelligent. They werepossibly more intelligent than modern humans for at least two reasons I can think of off the top of my head: there were far fewer generations to contribute to genetic deterioration; and quite long life spans which allowed for extended study, learning, discovery, invention, and specialization.
Plato records that Atlantis became perverse and immoral, and that it was destroyed by flood purposely by the gods to punish it for its wickedness. And Genesis records nearly the same thing of the world that perished. It could be that the Greeks, who were descendants of Japheth, passed down the history of the world that perished through their generations, but as the past became more and more distant, the Atlantis myth is what remained in their culture of the history of the world that perished by flood.