Marvel didn't create the superhero, but they created many who became icons. One concept that Marvel popularized and adapted for many of its biggest heroes is the secret identity. Over time, the number of heroes with secret identities decreased. Many of Marvel's greatest heroes had basically become government agents, working closely with SHIELD. As a result, public identities are much more in fashion than the old-school secret ones.
Source：https://www.cbr.com/secretive-marvel-heroes/
