As I don’t read Captain America comics (with Steve Rodgers or any other character being called Captain America), I cannot comment on stories.
Superman – Kal-El – Clark Kent is a leader, be it with the super-family or with the Justice League (comics).
Superman gave his life to protect the people and his adopted home world from Doomsday.
When Superman lost his powers (for a time) he still did not hide away, but continued the fight for Truth, Justice, and the American Way. Even now in the current War World story-arc, a powerless Superman is still fighting for liberty and freedom.
His deep love for Lois Lane (and them getting married, etc), and his life as a mortal (reporter).
Superman is a world-widely known IP, loved my many.
Captain America, IMO, is not on that same level.
For example, I know Peter Parker/clone story arc, I know of the Peter Parker/Doc Oct mind/body switch, I know Spider-Man rogue gallery (before the movies), etc. even though I don’t collect/read Spider-Man.
For Captain America, other than what was in the MCU (and his arch nemesis the Red Skull I knew before the MCU)… and how for a while they had Caps an undercover secret agent of Hydra, what has Caps done that those who don’t read Captain America’s comics can compare with?