Good vs Evil.
If you can get past the American propaganda then it is quite a good movie. Steve Rogers does a good job showing the transition from a boy gaining strength and power to a true leader. The visuals and scenery presented also enhance the good vs evil fight. This is a film that can be easily enjoyed by not delving too deeply into the story. If however you wish to look deeper then there are also more subtleties to the story.
Here he shows that he also has brains and is selected to be the doctors test subject. The doctor gives Steve a serum and other stimuli which transform Steve's body into it's full potential.
The Nazi's have also managed to infiltrate the experiment and assassinate the doctor. This leaves Steve as a one of a kind and unique. Hence the US army don't want to risk their only super soldier and Steve is sent on a travelling sideshow to gain popular support for the war effort.
It is during one of these performances designed to boost moral among the troops that Steve meets the unit his best friend was sent to. A number of the unit were captured, Steve goes AWOL with the help of a few others and brings back the captured men. Now he has become more than just a poster boy.