Superman was created by a pair of Jewish-American men who, as kids, had absorbed the news of Jews in Europe being tormented and attacked. The idea of 'passing' as non-Jewish was something familiar to Jews around the world at the time, and a good argument has been made by writers like Harry Brod that this is where the creators got the 'secret identity' bit. Brod and others make the case that Superman was conceived of as a secret Jew who cuts through bureaucracy to go out and personally protect people who are obviously suffering.

This exact archetype that you describe did not exist before comic books. But heroes did. Sir Walter Scott's 'Ivanhoe' describes a character that was held out as a model for heroism and proper behavior for American and English youth from the early nineteenth century into the early twentieth century. No special powers, though.

Odysseus might come the closest to what you describe. He didn't have super powers, but he was a hero with tremendous ability in combat who adopted an alter ego before fighting to reclaim his rightful place in his own country.

In Norse mythology, Odin had the power to throw a spear and always hit his target. And he can see into the future. Odin was known for often disguising himself as a normal human. Does that fit the archetype that you are describing? Probably not quite, but it deserves a mention.

The Superman-type hero is a twentieth century invention. We find heroes with pieces of that archetype in history, literature and culture before Superman. But it wasn't exactly the same thing.