's Cap is a symbol of America, but more of our foreign policy than domestic issues:
As Steve Rogers, he starts off small and frail ("a 90 pound asthmatic"), but unwilling to back down from bullies. One pummels him in the alley, but he just keeps getting up to be hit again until his virile buddy Bucky Barnes chases the bully off. Adolf Hitler is a bully, and Steve won't back down from him, either, nor should America. Thus, America is never the bully, only the bullied or the defender of the weak from the bullies.
Steve might be weak, but what's really important to his status as a hero is his heart and soul. Not just anyone could've been made into the superhero Captain America through the injection of the super-serum formula. It took someone with a truly good heart, intrinsically anti-bully, to wield all that superpower in the correct, moral direction. The Red Skull was injected with the same formula, but look how ugly he turned out. That is, America is a benevolent superpower (and better looking than our enemies), intrinsically deserving of our power over others, since it's not our nature to use force wantonly.
Steve repeatedly lies, but only for a just cause, to get himself in the military to serve his country and vanquish evil. Despite his 4-F status, he's sure that his country needs him to fight as a man, not as a scientist or with some other skill set that doesn't involve muscle. Dr. Abraham Erskine, the German inventor of the formula, recognizes the determination of Steve in his willingness to lie for a just cause and enters him into the super soldier program. Realpolitik might make lies necessary, but that's not a problem as long as you remain true to yourself and your cause is just. We lie for good reasons, our ends are justified, and we are necessary for those ends to be realized. When the time comes, we'll jump on the grenade to protect you.