The original xenomorphs were created to terraform planets for the Engineers to live in. The Mural in Prometheus is an ancient xenomorph. Yes, the temple is alive. In Fire and Stone, we know the fate of Deacon. It turned into a huge living mountain. David will add the mechanical part into the xenomorph because he is a synthetic. I think David will end up like Elden in Fire and Stone. He turns into a synthetic Engineer but he ends up becoming a victim of his own creation which leads us to the big fossilized Engineer in Alien 1.