Thanos/THOTI became the Almighty Supreme Being of the Marvel Omniverse.
Anyone wants to challenge that fact, bring it! 😬
Thanos didn't know where Warlock was?
That's completely untrue.
Thanos instantly knew where Warlock was,
and WHAT Warlock was even doing there,
without ever being there.
Thanos overlooked Death for the same reasons he allowed Warlock to survive,
because of his sub-conscious will. (which has always been his catch 22)
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Thanos sub-consciously allowed Warlock to survive,
in order for Warlock to "witness" Thanos' "grand gesture"
that "grand gesture" being, ... healing Marvel by re-creating it.
This is Warlock's reply to Thanos after he finds the Time-Space gone,
when Thanos told him,
'I see no reason you should now not share the fate of your comrades'
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The Cosmic Anchor's domain is outside of Space-Time,
so one of two possibilities exist.
1. Either Thanos ONLY absorbed all of Space & Time. (not realms outside of it)
2. Atleza's realm just happened to be where Warlock was at,
and Thanos wanted Warlock to witness his "grand gesture"
so he allowed Atleza's realm to survive.
Which is probably the reason why the ONLY other being that appears is Death,
it's not a coincidence that Thanos would sub-consciously allow her to survive as well.
Although Warlock attributed her survival to being located outside of Space-Time.
Imo, #2, and the reason I just explained why Death lived, fits.
Why?
Because in Starlin's interview, which I have the link for if you're interested,
he explains that the ENTIRE Marvel Universe was destroyed by Thanos.
He states that originally it was going to be non-canon,
because destroying all of Marvel for ever was impossible,
so they supposed Jim place the story in a twin reality that resembles Marvel, but wasn't,
Jim didn't like the idea, he wanted it to be canon,
so he instead proposed Thanos re-creating the Marvel Universe at the end,
therefore allowing the story to stay canon, which of course, it is.