If I am making Captain America from Avengers I might go Valor Bard. His fighting is decent like everyone else's but second tier to the big guns of the party.
Hulk = Barbarian
Thor = Paladin smiting
Iron Man = Tricked out Wizard
Black Widow = Rogue
Hawkeye = Ranger
Captain America = Bard.
Valor bards are decent second string combatants and he inspires everyone all the time. Plus valor can give him blue chain mail and shield proficiency.

All his bard buff spells can be somatic component patriotic or noble pose, verbal component stirring speech.