If you haven't seen Alien Covenant don't ruin it by reading the spoiler!
I just saw Alien Covenant. If David "created" the traditional xenomorph that follows the face-huger-type gestation, and since Prometheus and Covenant are prequels (albeit loosely based prequels) than how does - millennia later - the crew in Alien (1979) encounter the same type of species given that the spaceship originated from LV-223 (Prometheus world) and crashed in LV-426 (Alien 1979 world).
