Like most superheroes in Marvel Comics, each superhero like Captain America has an alter ego. So, part of the character is a peak human and the other part is a superhuman hero with superhuman strength. So, Captain America probably has both peak human and superhuman strength. It just depends on who he is at that point. Captain America is never tired and he has great combat skills.
He is bullet proof and can heal extra well. His drinking abilities are way above par because it seems like he can never get drunk no matter how much he drinks. Also, if he was known as a World War II veteran, then he would be 95 years old if he fought at 18 years old. Therefore, the aging process has stopped for him.