I would really find it interesting if this universe established that the black goo, and thus the xenomorph, is a representation of evil in itself throughout the universe. The engineers found about it, possessed and worshiped it, but everything just went plain wrong with them. The xenomorph is ancient, as old as the universe itself. David, as many of you in this forum has suggested, is just trying to recreate something that is older than many of us can comprehend.