For some time now, History (that's their new name) has presented the Ancient Astronaut "hypothesis" as legitimate, even though the primary advocate of it in the 1960s and 1970s, Erich von Däniken, was shown to be a terrible researcher and a fraud.
But fortunately, one of the things that killed his credibility was a BBC/PBS documentary that showed how flawed his ideas were and how unresearched they were and how he used fabricated data/artifacts to support his contentions, and that documentary is on YouTube, though it is a rip from a VHS tape not in great shape. But it does have a bit of rarely seen clips of the late Carl Sagan.
Some of the scientific assessments of things have changed in the 30+ years since this video was made, such as how the Easter Island heads (moai) were moved, or the purpose of the Nazca lines, but still in the realm of what normal humans can do. And there are still things to study, but the alien hypothesis hasn't been useful in explaining any of these things. But archaeology does a far better job, even where it's incomplete.
There are mysteries to solve, so let's use the methods that work!