I simply disagree. I have no problem with pretend fantasy abilities existing, so long as there is a reason in-universe why my pretend character has them. A reason more coherent than "it would be cool if they did". The vast majority of fantasy literature does this. Why shouldn't D&D?
But, we've gone through this quite a bit, and near as I can tell, all you need is for someone to tell you the ability is beyond earth human.
And my thing is I think you should already know that stuff.
If we compare:
"You gain the ability to fly"
To..
"You gain the supernatural ability to fly"
From a real-world perspective (the one you insist upon using), they should be directly equivalent. No human you know or have ever known has been capable of independent flight. That this ability is supernatural from a real world perspective should be obvious to you and it should be obvious for most people.
It should be obvious in the same way that dragons and ogres and beholders and mages are obviously supernatural from a real world perspective. Yet I haven't seen you insist upon the game coding dragons and ogres and beholders as supernatural.
In addition, I think we differ in opinion on how much fantasy stuff actually gets explained in fantasy literature.
You've pointed to Game of Thrones a few times during these various discussions. How much of the fantasy BS that happens in that series actually gets explained in the books? The red god's deal, the white walkers, the faceless men, wargs, wildlings? It's been a while since I read them, but I don't recall an explanation for any of it.
In point of fact, I'd go far as to say that I think GRRM has made them deliberately mysterious, because I think he is of the opinion that their presence in the setting is more interesting and important than their origins.
I don't think that is uncommon in fantasy literature, and I'd wager that most of the fantasy stuff that exists started with "it'd be cool if.." and then got explained or not depending on how fun or interesting the explanation was.