Clark's character roots change multiple times, Golden Age Clark is a take no prisoner fighter. who has no problem with throwing bad guys off bridges. He is action adventure meets classic film noire and a bit of swashbuckling cockiness thrown in. Silver Age Clark is an Alien who longs for the glory days of Krypton, well finding himself in "wacky" adventures directed towards children's imagination. Bronze Age Superman is an attempt to go back to the Golden Age, and make Clark feel more "adult" again well also deals with the uncertainty and difficulties of the 1970s and attempting to give of a "classic" image. Post Crisis Superman is a look back at the Golden Age and the first season of the George Reeves tv show, well mixing in "modern" elements of the 1980s culture. New 52 Clark bounces around between multiple different "personalities" never seemingly able to be grounded, until well he's grounded.
When Jerry Siegel first made Superman, he created a super powered man who would fight for what was right. You see Jerry's father died during a robbery, when he had a heart attack well his store was being robbed. Not surprisingly then, Jerry created a being who could fight back against such crooks who scared his Father to death. A being who theoretically could have saved his father, and who couldn't be scared by a gun. Strong, just, won't take any crap from the bad guys these are a few of the basic personality traits of Clark's Superman mask. He's a pulp hero turned up to 11, a power house of a character, mixed in with some Torchy Blane, thanks to the beautiful and sexual desirable Lois Lane. Clark stops gangster, abusive superintendents at orphanages, crooked politicians, wife beaters, war mongers, and even the first super villain the brilliant, but mad, scientist Ultra Humanite, who wants to take over the world! His other world origins aren't that important, it is just background, mostly just an excuse to why Clark has powers. The Silver Age on the other hand would put Krypton front and center multiple times, something GA Clark didn't care about that much after he found out about his origins.
When Jerry created Superboy on the other hand things were different. For starters the higher ups had stripped him of his creative control over his Superman character. His original vision was no longer deemed acceptable, and DC wanted their characters to be more kid friendly. So Jerry created Superboy. A child character, who existed solely to play on the dreams of young boy from the age of 5-11. Which echoed into the rest of the Superman stories eventually, until eventual Superman is no longer fighting gangsters and murders but instead is attempting to figure out why Lois Lane has suddenly become the fattest girl in Metropolis? Most of the stories are surrounded with child like wonder, and ideals. Which makes sense, since they are stories written directly for young children. These aren't "All ages" stories with their roots in very human problems, but instead are tales of wonder and discovery.