This is the simplest explanation, indeed. In fact UFO sightings sharply increased starting in the 1940s which corresponds exactly to the period when military aviation research and experimentation took off.
(I quite like the idea of aliens drawing ideas from their spacecraft from our popular culture as a storyline, but not as an explanation for the phenomena!)
And stories of abduction by aliens often involved those aliens claiming to be from Mars or Venus before it was commonly known that those planets didn't harbor life, much less advanced civilizations.
And the archetypal "grey alien" didn't really become the template for modern alien abduction stories until Whitley Strieber popularized them in a book - many descriptions of alien encounters until that point were of "Nordic" human type aliens.
So yeah, either aliens are being careful not to appear more advanced than popular culture would allow (maybe to the point of appearing as angels and demons to humans when their view of reality was entirely dominated by religion and not science) or much of the UFO phenomenon is basically a meme.
https://web.archive.org/web/20121214172708/http://ancientali...
It seems much more likely that these assumed acts of God were a misunderstood natural phenomenon rather than extraterrestrial beings who we have yet to capture on camera. Considering how closely the depictions of the event match pictures of sun dogs leaves it as the most reasonable solution.
Yeah... sundogs are weird, leaping sundogs are weirder[0].