I've recently read some information and speculation on Superman's origins. This includes some misinformation and what I think is overly-imaginative perspective on the history, so I'd like to try to set some of that straight.
Long ago, I read in a major publication that Siegel and Shuster originally created a Superman character who was an evil mad scientist. That summary is almost but not quite true. The story itself is online, with minor legibility problems in the scanning. The actual plot is that a mad scientist uses meteorite fragments to create a potion that bestows great powers onto another man. That power corrupts the "Super-Man" and spurs the scientist to try to dose himself with the same potion, but is killed by the Super-Man instants before he is able to. The Super-Man loses his powers shortly thereafter, sparing the world from his otherwise certain domination. It is also worth noting that the powers of that Super-Man are altogether different from the powers of the hero Superman, being predominantly mental in nature (eg, mind control, clairvoyance).
A recent article in the USA Today offers some speculation regarding the creation of Superman, supposing that a robbery that killed Jerry Siegel's father (perhaps involving a gunshot) may have spurred the creator to invent a bulletproof hero. Moreover, a letter in the local paper from an "A. L. Luther" denounces vigilante justice, so one might suppose that Siegel chose that name (off by just one letter) for Superman's greatest enemy. In fact, DC writer Brad Meltzer supposes exactly that.
I am inclined in both regards to disagree, although only a brain scan of Jerry Siegel's mind at the time he was creating the character could tell us for sure. The "Reign of the Super-Man" story shows us that Siegel's first attempt to imbue a character with superpowers involved no such invulnerability. Nor did Siegel's second such character (Doctor Occult) have such a power. Superman was at the earliest Siegel's third powered title character (a sci-fi character named Jor-L also preceded Superman), and so the bulletproof power seems less central in his creative outlets.
And the primacy of Luthor among Superman's enemies is a later construct, perhaps owing to fan preference more than Siegel's. Luthor first appeared almost two years after Superman debuted, and was the second mad scientist he faced, following the Ultra-Humanite. There had been over 30 Superman stories before Luthor debuted. If Siegel was itching to villainize the letter writer, he took his time getting to it.
I have read various speculation that Siegel and Shuster's ethnic identity, as the children of Jewish immigrants, can explain their creation of a character whose home was destroyed, and thus came to us and became the best of us all. But the original concept of a heroic Superman placed his origin not on another planet, but as the child of a scientist in Earth's far-off future, and that his powers were owed to advanced evolution of our own race. Thus, he came to us not via space travel, but rather time travel. This idea, fully Jerry Siegel's, was later used as the "surprise" origin at the end of Mark Millar's story Red Son. Once again, an idea which tries to explain Superman by psychoanalyzing his creators fails to explain their earlier iterations.
Edit: I have not found confirmation to my liking that the first, never-published Superman story had the future, rather than Krypton, as Superman's origin. I found many sources stating that he was from Krypton in that story. If it were possible to read the story, I would use that as the definitive answer, but the story no longer exists. I'd like to see if a statement from Siegel or Shuster on the point exists. I emphatically retract the "future" claim in the absence of such information.
If one did seek to find Siegel's racial and ethnic bearings as the basis of his stories, one would be very hard pressed to explain the story line that introduced Luthor in 1940. Action #22 tells the story of war breaking out in Europe, with the aggressor having abruptly attacked another country. While fictional names are used for the two countries, it is clear that the story is patterned on Germany's recent invasion of Poland (which had already ended in German victory long before Action #22 hit the stands). Interestingly, the villain of that story was someone in the country that was attacked; if these events are seen as surrogates for the real countries, then Siegel made his villain for the story a Pole, not a German.
An even more surprising result is found in the follow-up, when Action #23 reveals that the fictional war was not actually caused by the surrogate Germany. It turns out that Luthor had manipulated events to create the war, so the fake Germany's leaders (surrogates for Hitler) are exonerated. On a fairly direct level, the Jewish writer of this story thereby created a fictional apology for Adolf Hitler. It makes more sense to conclude that Siegel was not so deliberate in providing veiled political commentary.
As Sigmund Freud once said, sometimes a cigar is just a cigar. I think Roger Ebert expresses my take on psychoanalyses of Siegel like this:
When I was in college, we used to do "source studies" for the plays of Shakespeare, reading the books that were allegedly in his library and trying to figure out where he got his ideas. ... My source studies were always ungainly, disorganized and filled with wild surmises ("Shakespeare was undoubtedly referring to . . .").
Wild surmises are interesting. I can add my own: Eliot Ness, after bringing down Al Capone, moved to Siegel's own Cleveland and began a one-man war on crime. The year, 1934, just in time to inspire Jerry Siegel's idea of a one-man war on crime. Was this an influence on Siegel's stories? Or a coincidence? How could we possibly know? At least we know that at Nuremberg, none of the Nazis on trial claimed to have been following Luthor's orders.