I agree, racism is the core of most "ancient astronaut" foolishness. Remember that until the Eiffle Tower was built the Great Pyramid was the tallest human-made structure on Earth! People looked at the marvels of antiquity and just assumed that since modern people would have trouble duplicating them that the ancients couldn't have created them. Which is hogwash, of course. Many ancient cultures had some very advanced knowledge of specific areas. For example, after the fall of Rome the secret of making concrete was lost for about 1000 years!

It's interesting that for all their knowledge in some areas, the aboriginal peoples of the Americas never really learned to work iron or create steel. Essentially they remained stone/bronze age. I've heard it suggested that this could be explained by the "Beast of Burden Theory". It postulates that without horses early Americans didn't have the power/means to mine and work iron. I dunno, it could be. Horses died out in the Americas tens of thousands of years before humans arrived here and weren't reintroduced until the Spanish first came to the "New World." Certainly it wasn't for lack of intelligence, nor a lack of need. The natives were quick to understand the usefulness of steel once they were introduced to it.