[Bon mots]

The assumptions are:
They don’t need minerals, ores or metal, they need human DNA.
They want it covertly.
They don’t want to get shot down in the process, so best to throw a bone to the military minds and give them a few toys they will likely not master and move on with their program.

The folklore is interesting and there are a few credible stories out there amongst all the kooks. A few.

[fattigermaster]

Not saying how much of it's true, but some of the points this guy lays out in this video are pretty interesting. A main topic is clues that humans and many domestic species may have been bioengineered, and ancient civilizations possible contact with aliens and calling them gods. I don't ascribe to the overall theory he presents, but some of the evidence sure set me to reading/researching, especially about what we know of our oldest civilizations.

The alien factor put to one side, I am prepared to believe that we may have reached a previous high state of technology pre-cataclysm, whether with the help of extraterrestrials, well, I can entertain the thought but it's up to how you interpret the ancient texts and the DNA anomalies. Thought provoking, for sure.

There's a few other vids on YouTube on this particular vein of "Ancient Astronaut" theory but this one is entry level and covers the bases. I found it interesting, at any rate, when I first stumbled across it.