In terms of Marvel's superhero roster, Captain America isn't the hero you think of when the topic of smart superheroes comes up. Between Iron Man's technical genius, Mister Fantastic's quasi-omnipotence, and Professor X's psychic knowledge, the star-spangled man comes nowhere near the ranks of heroes you'd expect to be outdoing others.
But being underestimated like this is exactly how Cap manages to outsmart people so often. Nobody expects America's perfect golden boy to be capable of getting the better of them, and he uses this again and again to his own advantage. As such, Steve Rogers has managed to one-up people you'd never expect he could - with the likes of Nick Fury, Maria Hill, and even Iron Man among these ranks. He's no Batman or Bruce Banner, sure, but he's also far smarter than many people think he is - and more than capable of turning any situation in his favour.
While he isn't always the perfect standard of human intelligence, Steve is good at what he does, which is making the world a better place - and he's willing to outdo just about everyone on Earth in order to do so.