My ancestors were aliens.... Say I go back in time billions of years, my ancestors then would be aliens. Every element of our bodies is part of the phenomena we call the universe, therefore my ancestors true origins come from space.
All real science is ultimately based on evidence, not opinion or authority. Whereas the fundamentalist version of the biblical story of Creation can be shown to contradict the evidence provided by fossils, geological studies, DNA analyses, cladistics, and direct observation of evolutionary processes, no such contradiction has been seen so far with evolutionary theory. Hence, the evidence favours (strongly) evolution over Creation.