Well, the paintings were maps. Apparently precise enough that they could find LV-223, despite how ancient they were.Only Shaw suggsted they were invited. Their origins were merely depicted in cave paintings.
(in fact, I'm not sure how one would deduce those paintings have something to do with the origins of mankind... did I miss something?).
Maybe not just humans, but we're to understand Earth was targeted, right?Not just specifically humans. Just a weapon.