It also doesn't really answer the interesting question -- if one presupposes a "progenitor civilization" that gave rise to later civilizations, how did the firs

It also doesn't really answer the interesting question -- if one presupposes a "progenitor civilization" that gave rise to later civilizations, how did the first civilization start? It's not unlike the arguments for "panspermia" -- the claim that the origin of life came from outside Earth in a meteor. That just moves the interesting question of life's origin farther back in time and space.