Eternals is out on Disney plus and I just heard a great theory that is pretty cool. What if the Avengers caused the events that took place in the Eternals Movie by undoing Thanos’ snap? What if Thanos was the hero of Endgames and the Avengers were the villains?
So if you have seen the movies the Avengers and Thanos are referenced in it. At one point, Dane asks why the Eternals didn’t help fight Thanos. We know Thanos is an Eternal himself with some Deviant mixed in. So Thanos would also either not know about his history, or actually know and his drive to cut the Earths population in half would prevent the Celestial from being born, as the earth’s population would not be close to the magic number starting the events of the Eternals movie. So when the Avengers undid the snap, returning the missing half of the population to return, the set off the chain of events allowing for the celestial to be born.
So there you go, Thanos was the hero of Avengers Endgame, and the Avengers were the unwitting villains.