@Qingu I can’t stress this enough, but I neither believe nor disbelieve all the “alien visits the Earth” stuff. I feel that’s important to stress and repeat.
Because, any assumptions that we make about aliens, if they exist or existed, is flawed. Your reasoning will probably not apply to beings that are completely alien to this Earth and the culture. Not to mention technology.
For reasons dealing with really, really long commutes, I’ve spent a lot of time trying to figure out how things might go, or not go, if there had been visitations. Two things I always came up against were the psychology of aliens, which I’d never be able to figure out without actually having an alien, and technology.
Since I can’t address the psychology, I’ll make a point about technology.
If you read a passage from an ancient text that went along the lines of this:
“And then the god Xenu wrote on his clay tablet and showed me a picture of the world that appeared. He touched the tablet again and the picture disappeared.”
If you were studying that text twenty or thirty years ago you’d think, “Wow, a magical clay tablet.” But now you’d think, “Huh, the gods had iPads.”
Why don’t we see alien litter? Maybe they were very “green” and their stuff broke down after a few years. Or they perfected nano technology and after a certain amount of time little nano bots were activated to break down all the materials.
But, boy, do I love this stuff as a thought exercise.