"comic books suffered... from a bad case of the carbon copies. Everything was a version, sometimes hardly altered at all, of a newspaper strip or a pulp-radio hero... Consequently, the comic book, almost immediately upon its invention, or soon thereafter, began to languish, lacking purpose or distinction. There was nothing here one could not find done better, or cheaper, somewhere else...
Then in June 1938, Superman appeared."
-- Michael Chabon
The Amazing Adventures of Kavalier and Clay
Number One
What the Beatles are to rock stars, what water is to beverages, what the Sun is to things in the sky -- Superman is to superheroes. The first was the best; the field started at the top and had nowhere to go but down. It's as if the first person ever to play golf had been Tiger Woods. Superman won the argument and the fight afterwards. Superman was painted onto bombers in World War Two and is tattooed onto pro sports stars' arms in the present. Superman was America looking to ancient Greece to say, brimming over with confidence, "You thought Zeus was tough? Get a load of our guy."
Comic books could be found during the decade preceding Superman, and some of the titles that became DC's publications roster began about three years earlier. Among the strips devoted to comedy, comic strip adaptations of novels, and pages devoted to trivia regarding science, sports, and various oddities, there were the heroes. They fought mad scientists and smugglers, racketeers and mysterious-looking foreigners. They were masters of intuition and fistfights. Sometimes their stories wrapped up in a few pages, sometimes they ran for several issues. They always caught the bad guy, made witty remarks, and got the girl if there was a girl to get. Their stories had all the adventure a boy could wish for (and not get) in his own life, and they were so formulaic as to lack all suspense whatsoever once you'd read ten of them, which you could do in an hour.
The Creators
Jerry Siegel and Joe Shuster, teenagers from Cleveland, Ohio, were part of that early history. They wrote and drew, respectively, four strips in early comic books: Doctor Occult, Spy (starring Bart Regan), Slam Bradley, and Federal Men (starring Steve Carson).
Taken from those features and the earlier story Reign of the Super-Man (readable here) many elements of the eventual Superman character had already appeared in one way or another in other places. Most notably, Joe Shuster tended to draw all of his heroes the same way, so you would have trouble distinguishing Superman from Slam Bradley, or either of them from Bart Regan, or any of the three of them from Steve Carson. Their women also tended to resemble Lois Lane, and it was a recurring theme for the hero to have a pesky, but attractive woman interfering with -- and inspiring -- his heroics. Their heroes, of course, always win in battles of wits and fist fights alike. They even had bald foes, cuing the Man of Steel's first foe, the Ultra-Humanite, and his most enduring foe, Luthor. Interestingly, an unpublished story idea for Superman titled The K-Metal From Krypton would have revealed his secret identity to Lois and made her a partner of his. This, too, was part of the Siegel and Shuster template: Bart Regan and Doctor Occult both acquired female partners, while Steve Carson and Slam Bradley had females tag along to help them on a more temporary basis. Completely outside the context of the Thirties, one Federal Men story had a flash-forward to a possible distant future, and featured a policeman adventuring on Mars under the name "Jor-L", the name introduced in 1939 newspaper strips as the Kryptonian father of Superman. Doctor Occult had been seen flying with a cape as far back as 1936, but this was a one-time event aided by a magical belt. And Slam Bradley hailed from Cleveland, also the setting of Superman in the earliest Action Comics before the fictional Metropolis was created to be his home.
Up, Up, and Away
Though many of the elements of Superman were derivative of earlier work by Siegel and Shuster, there were at least four strokes of brilliance separating Superman from any earlier works. One, he was the ultimate American immigrant, hailing from another planet and (great wish fulfillment for boys whose fathers had been born in Europe) being excellent precisely because he was from somewhere else. Two, he had great powers that were a part of who he was, not temporary endowments like the powers that Bill Dunn acquired by ingesting minerals from a meteorite in Reign of the Super-Man or that Doctor Occult acquired thanks to magical devices. Three, the flashy costume. Although he actually wore it only occasionally in some of his earliest stories, Superman became readily identifiable by his costume; a good thing since you couldn't tell him from Slam Bradley otherwise. Fourth, and essential -- the secret identity Clark Kent. While Slam Bradley had a clever but physically puny friend/assistant named Shorty, Superman essentially was his own sidekick, and at the same time, had a metamorphosis that could let the most insecure reader imagine himself shedding his everyday identity and becoming someone wonderful.
Imitation is the sincerest form of flattery, and the true testament to Superman's success was the avalanche of superheroes who followed. What was a trickle in 1939 became a flood by 1941, with enough heroes being created to fill the sales racks, with their names more often than not being some word followed by "Man".
When a chemical solution is supersaturated, it has more of the solute than really should exist dissolved in the solvent, and when any additional change takes place, the solute suddenly consolidates. This phenomenon -- even its name -- is an apt analogy for what happened with Superman. All of the ideas that had been lying there separate in different characters came together, suddenly, and changed the medium, filling it with more Supermen (even if they had to go by other names like Captain Marvel and Aquaman).
Truth in advertising is rarely so prophetic: An ad in Detective Comics #15 announced Action #1 by saying, "You'll miss the treat of a lifetime if you fail to buy a copy!" Indeed, if you were alive then, you missed a treat of a lifetime if you didn't. Because not only did you miss out on the debut of Superman, but you also missed the opportunity to invest one dime on an object that would later be worth one million dollars.
Pulp Fiction
One of the best innovations that came with Superman may have been an accident.
The stories in most of Siegel and Shuster's early work (especially Slam Bradley) was achingly formulaic, on a par with the other stories in, say, Detective Comics (which ran Slam Bradley and Spy when Batman was not yet a twinkle in DC's eye). The hero becomes aware of a crime, goes to investigate, and easily defeats the criminal upon encountering him. There was cosmetic variation to this: He might learn of the crime via his boss, or via witnessing it himself. He might be captured before escaping, or he might just win the battle outright.
Siegel's first Superman story began with this same pattern, and you can read that story in Superman #1. However, because of space limitations, that story could not be published in Action #1. Therefore, the first four pages, which fit precisely the pattern, had to be deleted. Consequently, Action #1 begins in the middle of, appropriately enough, action, rather than an editor receiving a phone call that tips off Clark Kent that an injustice is taking place.
While the greatness of Superman has to be judged by the major elements making up the character, it very likely helped him make a splash to have his story break the pattern that was so common and to begin instead with action. Quentin Tarantino cut up his film Pulp Fiction and rearranged the parts to make audiences scratch their heads and think more about his plot. Jerry Siegel had the same thing happen to him by accident in a magazine that was pulp fiction.