Science fiction gave us a new way of gesturing at what it would be like to transcend humanity; you can call it a new set of tricks for simulating awe. “Tricks” because nobody has yet transcended humanity; if anything humanity is difficult to imagine minus our wish to transcend our limitations — so you could say with equal justice
a)nobody has every described what it would be like to transcend humanity because if they had done it, their readers would have done it, and they haven’t, so they didn’t
b)every human being in history has constantly been in the business of transcending humanity; that’s what being a human being is.
But the feeling of our limited conceptual and emotional and aesthetic resources being overwhelmed is a real feeling — the sublime, Kant called it — and we say as well that it is awe.
How does science fiction talk about awe or the super-human? By describing human beings in naturalistic terms and then inviting us to extrapolate. Either extrapolating a superhuman individual, like the high IQ supermen of Keyes’ Flowers for Algernon or Stapledon’s Odd John or Sturgeon’s “Maturity”, or extrapolating a future evolution of the entire human race — Stapledon’s “Last and First Men” — or extrapolating super-human aliens, or in a combination the future evolution of humanity uplifted by aliens.
In all these cases it is the gesture towards the unknown that thrills. Microcosmic God ends with the author in the dark about the future evolution of the super-evolved neoterics. Mimsy Were the Borogoves ends with the children, uplifted by toys from the future, inconceivable. It is always the same — a naturalistic lead up and then silence or amazement. Because, what else could it be?
Two exceptions that test the rule are the invocation of a group mind and the use of religious language. The future evolved humans may be free of individuality — Sturgeon’s “The Widget, the Wadget and Boff” or the group beings of “Childhood’s End” or they may actually become gods, or God. Neither is exactly satisfactory. The hive mind or group consciousness is just human consciousness splayed out among a multiplicity of bodies, and God, notoriously is a being who is either a human writ large or Inconceivability It- or Him-Self.