Well it depends on whether you are looking at him from the era of his creation (1938 to, let's say, the early 80s), or modern iterations of the characters (early 80s to now). Both are equally interesting but very different.Quoting Dukefrukem (view post)
While his very beginnings were fairly light newspaper fare (similar to every other hero of the era), he quickly became DC's Captain America. Fighting Nazis, inspiring Americans to join the fight, and adding "AMERICAN" to his resume as hard as possible without his outfit being a literal American flag.
I always found it fascinating how we got such wildly different characters and worlds out of DC with Superman and Batman, despite coming around at the same time. Both Gotham and Metropolis are obvious surrogates for New York City, yet Gotham portrays it as a practical war zone of crime and corruption, endless rainy nights and scummy characters. Batman is born out of near necessity. Gotham NEEDS Batman, and he is the only thing keeping its complete decay at bay. Whereas Metropolis is light, hope, sunshine. The people are good. Sure there is crime, but families are safe. Superman is there making an already good place better. Fast forward to the late 70s to mid 80s when comics in general started to "grow up" a bit. Artists and writers like Neil Adams, Marv Wolfman and Frank Miller start to give our heroes some gravitas.
We got like 30 years of incredible Superman stories between the 80s and 2010s. Stories of Superman losing everything, accepting death (both his own and his loved ones'), having a family, and a heartwrenching story of his deep desire to meet his birth parents.
"Fascinating history lesson, meg, but how does any of this make him an interesting character?"
First off, I find his unfettered optimism infectious and inspiring. A person with a deep-seated and unattainable need to connect with his world and people, lost in space and time, and yet he chooses to see only the good in others, to always help no matter the cost to himself. The importance of Ma and Pa Kent in providing him love and acceptance while also understanding that they can never replace what he never had.
And speaking of the Kent's, Superman is really like the ultimate "nature vs nurture" case, is he not? Several stories over the years have tackled this idea of "what of Krypton remains in him, and is he ever really a person of Earth?" Duke mentioned Red Son, but I actually much prefer Mark Waid's Superman: Birthright for this. What if Superman was only the first Kryptonian to arrive, of many on their way? What if he was meant to be the scout for an invasion? Which people will he stand with - the people of Earth who raised him, or the Kryptonians he feels he belongs with? This is one of the best Superman stories ever told, and has one incredible emotional punch of an ending.
The dichotomy of Superman being all powerful while also being so very vulnerable is something that goes back to Greek and Roman myths (and further, I'm sure). In Grant Morrison's All Star Superman, we see him having to accept what we always thought couldn't happen - his own "natural" death. Having flown too close to the sun and soaked up too much of its energy, Superman is getting ready to supernova like a dying star. This 12 issue series traverses an array of emotional and introspective Superman moments as he gets ready to say goodbye to Lois and the world.
In my personal favorite, Superman: Secret Identity, a guy named Clark Kent who grew up in Kansas in "our world" (Superman exists in pop culture and is a work of fiction), discovers that he actually has the same powers and abilities. While not a true Superman story in the strict sense, it still reveals much about Superman's inner workings. Being an outsider, being the only one like you on the planet, the moral dilemma of revealing yourself and your abilities.
As a kid I was very sickly. I pretty much grew up in and out of hospital. A complex.immune deficiency which led to 3 years of chemo, a fractured spine, suicidal depression from the age of 12. Through all of this I read Superman books and watched Christopher Reeve fly across the screen. It was cathartic for me, seeing someone who couldn't be hurt and couldn't get sick. Who could fly. But of course those aren't traits that make him interesting.
He is God, named Clark. He is a weapon that doesn't destroy, it mends. He is a stranger, but also the best friend you could ever have. He is a rejection of the belief that "absolute power corrupts absolutely". He would himself reject the idea that he has any more power than any one of us. Power to change, to make lives and circumstances better.
He is what we all wish we could be. A better friend, husband and person. Not just strong, but brave. Not invincible, but resilient in the face of adversity. A light to show the way.