Remember Martial Art movies where characters are able to do incredible superhuman things?
You see them fly through the air effortlessly, bust through brick walls, etc.
The premise is that they had to train hard to be this way.
The reason many accepted this is because it's still within the realm of the suspension of disbelief.
This is how comics work, relating to humans.
The characters aren't meant to be superhuman but that they are able to do incredible things due to training.
One simply can't be human and do superhuman things. This is a contradiction. If a human does something then it's proof that a human could do it.
Another angle is that comic humans are different than real humans. And why not? Different universes have different rules.
So in summary, nothing Cap has done is superhuman in terms of humans in his universe. So he's NOT superhuman in his universe in physicality.