Just what resources do you expect aliens could extract from the earth, across interstellar distances, covertly, hiding the transfers from the other advanced nations on this planet, for less cost than they could extract those resources closer to home?
You can try and figure what else they are afyer, but they are not here for our good.
On what do you base your assumption that so-called "aliens" came from "across interstellar distances"?
Since the 1970's, most people who have followed this subject closely have concluded that, whatever these things are, they are interdimensional or perhaps even what we humans might call spiritual in nature.