[Marvel] What if the Celestials never came to Earth?

In the Marvel Comics canon, it seems like an enormous amount of what happens hinges on the arrival of the Celestials. They experimented on early humans, resulting in the creation of mutants, Eternals, Deviants, etc. They also sunk the continent of Lemuria, the home of the Deviants, indirectly caused the sinking of Atlantis, drove off all of the different pantheons of Earth gods, etc.

If the Celestials had never come to Earth, how would the history of Marvel be different?