Here's more on the subject from a good poster named Texcap on comicboards that I enjoyed.
The "peak" designation given to athletes is simply not an all inclusive word. It cannot be all inclusive given it's actual meaning[s], and it's applicable nature to any number of qualified individuals. Muddled further by the very fact that Marvel does in fact apply it's own unique spin to the phrase "peak human" in a cannonical manner.
It's not a question of physically normal characters (in the M.U.) doing "super" feats, we're all very aware of the fact that Marvel's "normal" folks do amazing things -- things that we couldn't fathom in the real world -- but what's being missed is that beyond the built in, irrefutable, explanation that Captain America is "enhanced," is that Marvel has gone out of their way over the course of 60+ years to draw a distinction between (a) impressive human combatants, and (b) it's very select few: "peak humans."
(And while the handbooks may not be good for much, even they recognize and account for the physical distance between an impressive athlete, and the "peak human." With the "peak human," as they categorize it, being an unnattainable standard outside of artificial enhancement.)
Hawkeye, for example, has tremendous upper body strength. Within the pages of the books we've seen him perform feats of strength that athletes larger than himself were completely unable to (drawing his compound bow being one of them) and it has been pointed out that his uber training from childhood, with the bow, has contributed to his condition. Yet, Hawkeye himself tells us that he is no Captain America in terms of physical ability. Daredevil -- a "peak athlete" if there ever was one -- a man capable of shouldering weights that belie his size to the astonishment of verifiable strong men, yet capable of doing a triple back flip as if he were walking backwards draws the physical distinction between himself and Captain America. These characters absolutely perform "super" feats as we might view them -- but that's not the kicker. What is, is the fact that Captain America, himself, enjoys another category of ability than themselves all-together -- and always has. It simply means that with everything they do that's impressive, Cap's ability is simply physically "beyond" it.
Hawkeye - Impressive athlete, natural conditioning.
Cyclops - Impressive athlete, natural conditioning.
The Falcon - Impressive athlete, natural conditioning.
Wolverine - "Peak Human," artificial enhancement (Weapon X process).
Black Panther - "Peak Human," artificial enhancment (Wakandian herb).
Captain America - "Peak Human," artificial enhancment (Weapon I process, "Super Soldier Formula"😉
The difference? The "Peak Human" body does not follow natural ability or limitation, it has been enhanced to account for an unnatural physical ability.
Why? Because Captain America was "made" to actually be "preternatural." To be able to accomplish, what the "normal" human could not -- his entire purpose for being, so far as the military experiment was concerned. No human, outside of enhancement, has the physical capacity to shoulder what Cap is capable of aggregately (comic characters included, natch). No character, outside of enhancement, has an immune system capable of filtering deadly poisons out of they're body in a matter of minutes (if not faster). No character, outside of enhancment, has the ability to overcome fatigue to the degree that Cap is capable of. No character, outside of enhancement, enjoys a dramatic decrease in aging. No character, outside of enhancment, can endure the temperature extremes that Cap is capable. This list goes on and on.
Cap can do it because he was "created" to do it.