Alien: Covenant - What Does The Ending Really Mean?

6. The Engineers Are Gone, Or Are They?

Having discovered the alien pathogen pay-load's weaponised purpose, David reveals in a flash-back that he turned it against the Engineers, killing them all on their homeworld for some reason.

Quite why he does this remains to be seen: it could either be because one of them pulled off his head, or that he suspected they created mankind and wanted to punish them for it or that he didn't want to have to potentially answer to any master. Perhaps it's just a combination of all three, as well as his desire to explore his own potential as a creator in peace?

Perhaps it's merely his commitment to the line from Prometheus: "A king has his reign. He dies. It's the natural order of things" - that he appoints himself the deliverer of that inevitable fate, just as they killed Weyland looking for his own immortality.

But are the Engineers really gone entirely? Their destruction makes the appearance of the "space jockey" seen in Alien somewhat confusing: its warning about the Xenomorph danger doesn't really make sense unless it died after this point (unless it was a rogue railing against its own species' attempts to make the Xenos?)