The first X-Men forever put forth the idea that the Celestials implanted the x-gene into its humans so that they would one day take the place of the Abstract Entities. This is the series that first called Jean and Iceman "Omega" level mutants.(Obviously Rachel was the first mention of the term by Nimrod back in the 80's...)
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So, it's been established as a pathway. Obviously many things have changed over the years. I detest them having made the Eternals 3D printed robots for example. Kirby clearly established his Eternals, Deviants, and humans(with the genetic potential for powers, aka the X-gene, already inserted, but largely dormant in the vast majority) as being siblings or at least cousins all descended from the exact same group of proto-humans indigenous to earth. The Deviants were programmed for infinite mutation with various forms. The Eternals were programmed for godliness, and very soon developed themselves with their own scientific experiments to become capable of channeling cosmic energy and be superstrong/fast/psychic/etc and immortal. They literally just lived that long. Humans were programmed for a bit of both, so there's variety of form and variety of godliness.
The modern take on Eternals makes them manufactured and respawn from "the machine called Earth", and the leaves the Deviants as the only direct progenitors of human mutants, and they are just the result of a dead Celestials' necrotic fluids seeping into the ground, and it just grates me to no end. I wish the MCU had taken more from the Kirby originals, and less from the modern muck(that movie was almost good despite itself, if only they had introduced the concept of mutants there, maybe even cameoed young Selene or Apocalypse along the way).
But it's that Celestial-placed X-gene that is behind all the superheroes on earth being so strong and influencing everything beyond their somewhat sleepy planet on the cosmic scale and even interdimensionally. The Celestials wanted great things from the humans of earth. That can be naturally activated(mutants), or activated externally through a catalyst(mutates like the FF, Spidey, Hulk/etc.), and also Inhumans (though they have additional Kree manipulations activated with Terrigen), but all their powers are actually coming from the same [Celestial]source. Anyways, long story short, there is a clear path for Omega mutants to become Cosmic Entity level beings, or even greater! And I wouldn't take Storm there often, but I see that sort of story being her endgame, which we also somewhat saw in Ages of Apocalypse's immortal elemental Storm, and the Black Vortex's Storm who was showering planets with asteroids. The potential is there(such as when she hosted Eternity in her body without going insane).
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