I have always been interested in the idea. Erich von Däniken often gets dismissed by mainstream scientists simply because some of the examples, that he suggested may be evidence of ET intervention, have more probable terrestrial explanations. There is no doubt, for instance, that Ancient Egyptians were able to build their monuments without the help of ETs. However, the hypothesis that we have been visited in the past is not stupid, regardless of whether it is correct. Unfortunately, because of the popularity of the subject, it is drowned in the wild speculations of tabloid journalists.
In my early teens, I was intrigued by maps in Colliers Encycopedia that showed how a new race, which I think the maps called late mongoloid, emerged out of what I think they called early mongoloid. The terms have probably changed since then. In the article, early mongoloid meant e.g. Native Americans and late mongoloid meant e.g. modern Chinese. However, although what they called late mongoloid people were presumed to be descendants of early mongoloid people, it did NOT mean that the late mongoloid peoples were in any way superior to the early mongoloid peoples. By coincidence, not very long after being interested by that article, I read The Midwich Cuckoos by John Wyndham. In that novel, there is a suggestion that the advent of late mongoloid people was the result of intervention by ETs.
The Ancient Astronauts hypothesis was popularised but not invented by von Däniken. In some of his stories, H P Lovecraft suggested that ETs had settlements on Earth long before humans existed, and that all life on this planet is the result of their experiments, as well as evolution that took place while the aliens were away or, more typically, slumbered while waiting for Earth's environment to become inhabitable for them again.
