This is a key point that a lot of people don't seem to get.
The evidence, I would suggest, actually weighs against humans in D&D being biologically identical to humans in the real world. That's a lengthy and fraught topic, but certainly you're on the better-evidenced side of it.
Further, the belief that the martial-magical divide is absolute is, frankly, an awful and senseless belief that only causes problems, solves nothing, and offers absolutely no benefit to anyone. It cripples the entire game like a sliced hamstring. This isn't novel thinking either - Earthdawn, the first real, non-heartbreaker-y attempt to make a "D&D that worked" recognised this, and destroying an ability to believe in that divide as an absolute was one of the first moves it made.
In the section that covers humans, their age ranges, heights, weights, lifting capacities, etc. The D&D human is meant to be the point of comparison, the 'control', against which everything fantastical is weighed so that we, the player, can relate it to our real lives.
It doesn't, as a pure matter of indisputable fact, say anything of the sort. To suggest that it does is simply an outright falsehood with obviously no basis - it's funny but it's nothing else.
Now, separately from the facts, you are entitled to an opinion that, because humans in D&D have similar (though not identical) age ranges, weights, lifting capacities and so on to Earth humans, they essentially are identical to Earth humans, but that's not a fact, that's an opinion. Whereas the fact is, it's an unknown.
Further, it's not as well-supported as you seem to think by the facts of D&D, not least that in D&D, sufficient tough humans can literally leap from a thousand foot tower on to a stone surface and only survive, but not break a single bone or limb, perhaps not even be prone! If you want to argue things like "lifting capacities" as evidence for your opinion, you must accept things like falling damage as evidence against your opinion. And it's quite persuasive evidence, I'd suggest.