The Star map found on Earth

I agree... this is completely strange to me. There is little logic to this. I can certainly come up with some but nothing that makes for anything interesting and movie worthly. They just needed a provocative connection between the ancient human civilizations and these beings to kick start the point of the film...

Maybe if all went right they did not want humans to know where they lived before they could fully analyze them. Kinda of like a Test Planet (like the experiments), seeing if humans were worthy of joining them