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.