David created the Alien.
Confirmed by Ridley Scott at SXSW
Link -
http://www.cinemablend.com/news/1634600/ridley-scott-revealed-some-serious-alien-covenant-spoilers-at-sxsw "The final preview scene starts on Michael Fassbender's android, David, who definitely is the Prometheus android, and not the new Covenant android, in this scene. David escorts Billy Crudup's character through what The Verge describes as a "personal workshop of biological terrors" David is explaining that, in an effort to fully understand the alien that they encountered in the finale of Prometheus, he has been experimenting with genetic mutations of these creatures, and that he has genetically engineered new versions of the Alien. David says that he has been waiting for one last piece of his genetic puzzle to fall into place, at which point he brings Crudup's character into a room that contains the four eggs that we know from Ridley Scott's original Alien. David's final puzzle piece is "mother," or a waiting host, and he wants Crudup's character to be that for him."
(Warning, the above text you just read contains a major spoiler).
