Oh sry I didn't actually read everything, just react to the general idea that aliens came for gold or whatever (which I heard many times). IMHO the most unique thing we could offer in interstellar trade would be delicacies such as cheese and beer. Because they probably would not want tech or raw ressources... Maybe cultural things such as books, music or movies could be valuable too; if they weren't too easy to copy.
Actually, the "ancient aliens' believers generally state that they
uplifted humans from apes. e.g. that doesn't actually presuppose that they detected
us and then came here, since the entire point is that we
didn't exist yet. e.g. if apes didn't exist, they might have uplifted wolves or some other animal instead.
e.g. all that's needed is to presuppose that the aliens detected some life-signs here. Previously, it was generally assumed that meant they'd have to have sent actual physical probes to each and every star system, then get data sent back from the probe, then send the expedition. But that seems naive now, given that
we can already scan the atmospheres of many exo-planets from lightyears away. So the only thing such a race would need to notice Earth is a spectroscopic analysis of our atmosphere and to notice the high concentrations of oxygen and water.
But such a race is highly likely to be much older than us (since the chances of them developing space travel and arriving recently is extremely unlikely), so in that scenario you could imagine a race who send a bio-survey expedition once in every few million years or so, so they'd be extremely unlikely to have visited Earth in "historical" time. e.g. even if some ancient (many millions of years old) spacefaring race knows there's life on this planet, and even if they have sent expeditions before, they're extremely unlikely to have sent an expedition any time recently, or to know that humans are here, or that we have recently "teched up".
This is another reason "ancient aliens" believers usually state that the aliens
created our race and/or our civilization, because if there's a causal link there, it explains away why they would have arrived only a "short" time ago in the geological sense.