And he led the charge against Norman Osborn in Siege. Led the charge against The Serpent in Fear Itself. Was seen as the leader of the Avengers in Avengers vs. X-Men.And in Secret War he was repeatedly resurrected to fight cosmic powered Doom
The reason I am saying Captain America is "the hero" in the Marvel Universe is because he's treated as "the hero" of the Marvel Universe.
The other possible Golden Age contenders have marks against them.
Namor is... Namor.
And Jim Hammond fell from prominence a long time ago.
(And most of the other Golden Age Timely characters never hit anywhere near as high as these three.)