Originally Posted by
Revolutionary_Jack
That comes from Superboy. For those who don't know, in 1949, Superman was so popular that they wanted to do all kinds of new stories and ideas, and also target younger readers. So they came up with the concept of doing Superman's teenage years. This created a host of problems (which are problems for the writers and creators even today) because the story establishes that Superman only began his public career when he arrived in Metropolis and met Lois Lane and became the mascot of the city and so on.
But anyway, they decided to do Superman the Teenage Years, had the character be called Superboy, had all the action take place in Smallville, Kansas. And indeed it's because of Superboy that Smallville, Pa and Ma Kent, Lana Lang (who was created as a Lois substitute because they couldn't shoehorn Lois in his young days), Pete Ross and other mainstays. Superboy led to stuff like Legion of Superheroes and other stuff, Luthor was retconned into being a kid Clark knew from Smallville (and they created an origin for his baldness because why not). * (More on this but it's tangential)
In either case, the concept of a high school hero as far as Superman goes had a precedent in Superboy, and before Superboy you had Fawcett's Captain Marvel with Billy Batson and his Marvel Family who all became teenagers as the comics went into print. Remember, Spider-Man graduated high school in Issue #28 (and very few issues of the Lee-Ditko era actually takes place in high school)...and as late as 2000, there were far more issues of Superman in any continuity, as a teenage superhero than Spider-Man (and in terms of issue count considering how successful Superboy was, even more today).
* The entire Superboy thing has presented a problem for Superman as a character ever since,
1) That was really successful and defining for a lot of people, and those fans (Mark Waid above all) didn't like how John Byrne removed all of that Post-Crisis stuff. It introduced a lot of elements of Superman's supporting cast and tied into Legion of Superheroes which became this sub-franchise and removing it affected a lot of that, or created problems for that. So that meant a lot of people have tried to reconfigure Superman by trying to merge the timelines.
2) Logically, the arrival of Superboy kind of raised a lot of big questions about Superman as a character. If upon discovering and mastering his powers he automatically started using it to save people, why was he confined to Smallville for so many years before coming to Metropolis to become a world-superhero. Also from a continuity sense, how is it that nobody heard of Superman until he came to Metropolis.
3) Removing Superboy, unintentionally, created a problem because now the question was why did Superman spend a decade or so between his teenage years and so on before coming to Metropolis to become a superhero. What did he do all those years? Stuff like BIRTHRIGHT, and even Snyder's Man of Steel, mined this in their takes, for better and worse. Superboy at least answered the question saying 'he was Superman from the get-go' even if it made no sense continuity-wise...but what that means was that you had to provide a psychological basis for a character who, arguably (not that I agree but I concur this is valid) was never intended or capable of having one.
4) Adaptations like Reeve's Superman and the STAS kind of skirt this issue. If you see Christopher Reeve's first film, there's a huge cut and gap between him going into the Fortress of Solitude and then coming to Metropolis and meeting Lois, and ,that gap isn't explained.
Superboy is kind of the heart of the conundrum with Superman and Batman and Spider-Man. Batman having no powers you can easily explain any gaps as saying, "He was training and learning" and it makes sense and it fills space and you can tap into that to introduce and allude to stuff. Spider-Man since he became an active superhero from the age of 15 and we follow him as he has grown into his mid-20s, that means no significant gaps exist. With Superman though either he's Superman all his life, which doesn't make sense in terms of the classic and essential status-quo (Clark Kent at Daily Planet pining for Lois Lane), or that dude decided to become Superman only fairly recently and it took him ages to decide on his mission and identity as a superhero and champion of earth.
And you can see that with Spider-Man, Stan Lee and Ditko, both obviously knowing Superman and Batman were able to see the problems in the characters and find solutions. Superman was introduced as an adult superhero originally but maybe later on they thought he should be a superhero from his teenage to adult years, and have love interests (Lana, Mermaid girl) before finding "the one" in Lois. That was all retrofitted later...whereas with Spider-Man they were able to plot all that from the get-go step-by-step. You can see that in the Ditko era, where Spider-Man was in a love-triangle with Betty and Liz, neither of whom were intended to be major love interests for Peter, while Mary Jane was set-up and foreshadowed to be "the one".