Warning! Spoilers ahead for Eternals.
Eternals ending, explained
If you’re reading this, but you haven’t seen Eternals, here’s a quick recap of the ending — or at least the parts that matter for Thanos.
At the movie's start, we’re told the Eternals are aliens sent to Earth by the all-powerful Celestials to protect humanity from the evil Deviants (basically giant CGI tentacle monsters). However, as we later learn, that was all a big lie cooked up by the ancient and all-powerful Celestials. It turns out the Celestials created the Eternals out of synthetic material for a specific purpose that’s much less altruistic.
It gets a bit complicated at this point, but basically, the Celestials reproduce by planting a single seed in the core of a planet. The seed feeds off the energy of intelligent life on that planet, which, in the case of Earth, is humans. The Eternals’ job is to wipe out all the Deviants so enough humans can exist to fuel the seed until a new Celestial is born.
Oh yeah, and when the Celestial is born, the entire planet and everything else living there get wiped out in the process.
Thanos and the Eternals
What does this have to do with Thanos? Well, as Eternals reveals, when Thanos snapped his finger and wiped out half of all life in the universe, that set back the Celestials plans. All of a sudden, there wasn’t enough intelligent life to power the growth of new Celestials.
That means Thanos essentially saved the Earth from potential doom. (Then again, as some Eternals argue, the end of the Celestials might also mean the end of all life in the universe since Celestials have the ability to create entire galaxies.)
Regardless, for the sake of this movie, the Celestials are essentially the bad guys, and that means stopping their plan is a good thing. In other words, when Thanos turned half of the Avengers to dust, it was a net positive since without him a giant Celestial would have exploded out of the Earth and wiped out 100 percent of humanity.
Of course, that’s not what happens in this movie. Ultimately, the Eternals turn against the Celestials and defend the Earth (or, at least, some of them do). In the end, even without Thanos, someone would have come along and stopped a Celestial from exploding the planet. But hey, at least thanks to the Mad Titan, we got an extra five years before the Earth started to rumble.
Eternals is now playing in theaters.