are you suggesting they may not be highly advanced?
Not at all, I left open the possibility of different levels of advancement of the possible different species...Perhaps one is just a few hundred years more advanced than us, if so we would most likely be able to understand them better, at least their technology compared to a species that might be a million years more advanced...A species that far advanced, I would hazard to postulate, would be able to hide themselves from us so well, if they are interested in us at all to take the time to visit here, that we would not be able to detect them in any way...
If these structures are on the moon perhaps they were left by a species that no longer visits here, they abandoned their outpost for whatever reason...Maybe those structures are a million years old and empty...