well, LH... I am 'generally' familiar with your theory , but as you note, it doesn't have wide acceptance.
My own opinion is that any significant group such as you describe would have left artifacts and/or archeological evidence. Suggesting that those are now under "polar ice caps" is counter to the best geologic/climatological studies so far. (Even Atlantis seems to be gradually being identified as related to Minoan culture and the Thera/Santorini eruption)
We DO have some evidence of our remote ancestors which does not lead us that way....they were pretty primitive. If, as I suspect, you are hinting at some culture which was not our direct ancestors, but possibly alien, I can only shrug. I have my reasons for my skepticism, as you have yours for your suspicions/belief.