Both characters have tragedy as part of their origin. Superman's home planet Krypton exploded when he was a baby, and his birth parents placed him in a rocket and aimed him at Earth. Superman's tragedy is set at a distance from his day-to-day life, but Spider-Man's is much more personal. After gaining powers from being bitten by a radioactive spider—a reflection of the atomic paranoia of the time on par with Godzilla—Peter Parker chose to become a wrestler and try to make some money with his powers. Instead of doing good deeds with his powers, he made a selfish decision that led directly to his Uncle Ben's death, leaving his Aunt May widowed and adrift.

The shift in approach there should not be ignored. Instead of being a self-assured man with functionally infinite resources for fighting crime, Spider-Man is a lonely and bitter teenager who struggles to help his aunt keep the lights on. He is indirectly responsible for the death of a loved one, and that tragedy provides the fuel for his crusade. Instead of fighting crime as a show of his own innate goodness, Spider-Man begins to fight crime as a way to atone for his own sins.

Steve Ditko / Marvel Spider-Man still struggles with his day-to-day life like the rest of us, and that fact serves to pull superheroes down to Earth. Parker is thrust into the role of man of the house after his uncle's murder, and he struggles under the weight of that burden. He works hard for next to no credit, often ends up rejecting profit in favor of doing right and honoring his uncle, and puts up with a hostile working environment to make ends meet.

Steve Ditko / Marvel

He's still a teenager, however, and that counts for a lot. Underneath his mask, Parker is smart, but that smartness comes alongside the kind of bitterness that festers when someone feels underappreciated. He constantly thinks about showing up Flash Thompson, his primary bully, by humiliating or attacking him. This is less than heroic behavior by any definition, but you understand where he's coming from even as he's behaving poorly. He's a boy that's in over his head.

When he pulls the mask on, however, Parker becomes The Amazing Spider-Man. "Becomes" is the most important word in that sentence. He doesn't have the innate goodness of Superman, but he does have some idea of how superheroes are supposed to act. It's easy to miss, but the Spider-Man persona is an act. He's a teenage boy's swashbuckling, one-liner-tossing idea of what a hero is supposed to be like. He is suave, he is fearless, he is daring, he is cool, he is everything that Peter Parker wishes he was.

Steve Ditko / Marvel

That performance element is vital to understanding Spider-Man, and an inversion of the relationship between Clark Kent and Superman. Superman plays Clark Kent as square and uncool as he can possibly be in an attempt to secure his secret identity, but Kent and Superman have the same righteous nature at their core. (Kent is often portrayed as an investigative journalist, after all.) Peter Parker, on the other hand, is a teenager first and a superhero last. He has to work for his heroism. He has to remind himself why he fights. When his faith cracks and he quits, he returns out of guilt. He eventually grows into his own righteous nature and to embody the phrase "with great power comes great responsibility," but it takes some time.

Steve Ditko / Marvel

Spider-Man has failure at his roots, but he isn't defined by his tragedy. He's defined by the fact that he keeps struggling and striving to be the person his uncle knew he could one day become. Everyone knows what it feels like to have someone else's expectations sitting on their shoulders, and that's part of why Spider-Man works so well. Often times, Parker's personal drama seemed more dangerous and exciting than the cadre of villains who would do him harm. It's easy to figure out that Spider-Man isn't going to die, but disappointing his aunt, missing a date, or losing his job are all within the realm of possibility.