But Faerun humans can do things Earth humans can't, despite implicitly in-universe supposed to be descendants of Earth people.
Consider this. John Carter, Jeddak of Jeddaks, Warlord of Mars is an Earth human (supposedly, let's not get into how old he might be).
But on Barsoom, he's a heavy gravity lifeform on a planet with less gravity, giving him superhuman powers despite not explicitly (longevity aside) being human.
So one could easily state that being exposed to a world suffused with magical energy, coming from a world that doesn't have magical beasts and Elves running around could give you abilities beyond mortal ken. It's a very old literary trope.
And there's a lot of evidence to support this in D&D, historically. It's hard to prove if psychic abilities exist on our planet, even if someone pulls off an incredible thing, they probably can't do it again on command under scrutiny, at least with consistency.
But a D&D human could totally have psionics and be able to perform them again and again on command.
Now Micah, I know what your objection is. Despite all the evidence to the contrary, D&D never states that it's humans are not the same as Earth humans. Well, at least, not that I've ever seen. And it's a valid point that it probably should. One shouldn't have to use logic or deep dive into the game's worlds and mechanics to discern this fact. It should be obvious.
And certainly, mechanical arguments are difficult because it's hard to differentiate between "the game is making an absolute statement about the capabilities of (insert thing)" from "this is an abstraction for ease of play". Which leads to a lot of these same arguments.
I can prove that there are humans in Faerun who are not like Earth humans and do things humans can't. It was actually quite trivial to do in prior editions, a little harder in 5e, but still possible. What does that mean, though? What are we supposed to take away from that?
The game books stay silent on the issue, and for good reason- the idea that humans aren't humans might not be something you want in your game. And that's not necessarily a bad thing (I called it a mistake upthread, but that's mostly because I tire of some of these talking points, lol).
The truth is, D&D shouldn't tell you what isn't possible. It should tell you what could be possible. D&D is for everyone, everyone has a right to play and have fun in their own way. If that means you want to view the game with the default assumption that it starts with our world with exceptions, and that makes the game more enjoyable for you and your group- go for it!
You just have to occasionally squint and look the other way when there are exceptions that aren't stated. I mean, the core system has abstractions that we really shouldn't engage with because they make no sense, like, you know, hit points, armor class, and so on.
However, it's an equally valid way to play the game to look at these exceptions as defining the game's worlds and settings. I would say to a point, or you get a Tippyverse which does not resemble traditional D&D at all, but it's still valid, as long as the game remains fun for the players.
For example, despite explicitly being stated as being Earth in the past, there exist humans in Middle-Earth with abilities Earth humans don't have (Aragorn, with his High Numenorean lineage). Does this mean Men in Middle-Earth aren't humans? Or should we take it to mean that, in a world where magic is at a higher level than it is (apparently) on our planet now that humans have additional capabilities we don't seem to possess?