Thanos killed half everything! Every man, woman, child, animals, plant life, alien beings (including The Celestials). He meant what he said when he would kill half of life within the known universe. No one was excluded except those who survived the outcome.
When Thanos couldn't destroy cosmic forces, he locked them inside Eternity, the archetype of the universe, and saw Celestials as multiverse creatures and the Infinity Stones as one specific timeline/universe, the celestials and other cosmic entities would have been unaffected by the snap.
Thanos and the Eternals
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.
In the Eternals movie, Sersi said that the Eternals couldn't fight Thanos because they could only fight in conflicts that involved Deviants.
No Eternals Were Snapped Away by Thanos - Here's Why.
Arishem may have calculated a simple cost benefit analysis and determined that opposing Thanos given all of the aforementioned conditions simply wasn't worth taking the risk to himself.
Deadpool survived the Infinity War snap because he wasn't technically in the Marvel Cinematic Universe at the time. Marvel Studios boss Kevin Feige was asked about the Merc with a Mouth and jokingly gave the answer that certain hardcore McU fans have been wondering about since April of this year.
Thanos might have found out the truth of the Eternals and rebelled, he tried to appeal to the masses, but they didn't believe him. Then what he "predicted" happened, a Celestial broke through the mantle of Titan, decimating it. Every planet he conquered has a Celestial seed.
One Above All was one of the many victims of Thanos in his eternal quest to please Death. He was obliterated along his fellow Celestials by Thanos when he stabbed Black Bolt to death in order to use his destructive voice as weapon.
Doctor Strange watches against threats from other dimensions, but the Eternals are part of our dimension. If it is revealed later that Doctor Strange knows of the Eternals, then the reason he didn't ask them for help in Avengers: Infinity War is that Marvel Studios wasn't ready to introduce the Eternals yet.
Enraged over the Celestials despoiling the Abyss through their creation of the 7th Cosmos, Knull manifested a blade of living abyss from his shadow – creating the first All-Black The Necrosword – and decapitated the Celestial, thereby marking it as the first death in the renewed Multiverse.
The infinity gauntlet with all stones is the 2nd most powerful object in the marvel universe (after the heart of the universe) and with it, thanos can do almost anything including defeat the likes of celestials and galactus.
With no clear explanation of what planet it is, the idea is that the Celestial destroyed Titan with the stone. On the surface, the theory has strong legs, but the reality is that the planet destroyed by the Celestial came long before the destruction of Titan.
Technically, Gilgamesh and Sersi were the first Eternals from Earth to become members of the Avengers. But the first Eternal Avenger was none other than Eros, AKA Starfox. Starfox came to Earth in AVENGERS (1963) #232, and he immediately asked to join the roster.
No, the older gods' power is so far beyond what Thanos can do with the gauntlet.
After all, It's because some fans thought that Galactus is a celestial, but no. Galactus is not a Celestial. Both are considered space gods threatening to destroy the earth. Both are giants with unimaginable power and have very similar wardrobes in the comics.
Notes. One Above All is the most powerful of the Celestials.
Despite the Astral Regulators' incredible power, Thanos gained control over them and subsequently used their power to defeat TOAA. This allowed him to absorb The One Above All's powers and become the most powerful being in the multiverse.
The Celestial known as the “One Above All” is definitely below the power of the abstracts. Think of him as the upper end of power for a celestial. Celestials don't vary that much in power, but the more powerful ones are usually the ones in stories.
Thanos wanted to preserve life in the universe (with very questionable methods, though), and The Emergence, which meant the destruction of entire planets, went against that. The snap would have become even more important to him as it meant the delay of The Emergence, thus saving planets and lives.
Thanos is not a robot.
Is Thanos a Celestial? Strictly speaking, no. Thanos is not a Celestial.
Thor survives, but he doesn't stop Thanos from destroying half the universe. Black Widow/Natasha Romanoff: Black Widow takes out several of Thanos' children in the battle in Wakanda and survives the fight.
Thanos is jealous of Deadpool's relationship with Death and T-Ray is to "curse him with immortality" so that he may never see Death again. In the end, Deadpool destroys the artifact and all the copies, but not the real Deadpool, are drawn into T-Ray, destroying his mind.
While the Avengers debated who could wield the Infinity Stones and save the universe, Hulk was ultimately the one who was deemed strong enough to survive reversing Thanos' snap. It was the ultimate heroic moment for Hulk, as he even stated, "It's like I was made for this."