"...Well, I did some exploring in my teen years, and a few of the species I encountered hadn't heard of aliens before. We couldn't communicate very well, but I helped them out where I could, and tried to leave on good terms with their leaders and planetary protectors. But the more significant story, I think, is from when I was a small child.
"My real name is Kal-El. I come from a planet called Krypton. Krypton was a rather advanced planet, full of genius and technological wonders, but it had a flaw -- an instability in its core would eventually cause it to explode. My parents, Jor-El and Lara, were scientists who realized the death of Krypton was approaching, and tried to warn Krypton's leaders, but many people refused to listen and the few evacuation attempts failed. In a last ditch effort to save any part of Krypton, they placed me in a prototype rocket just big enough for one passenger and sent me in the direction of the first inhabited world they could find, a planet called Earth.
"Sometime after my arrival on Earth, I came to a rural town and revealed myself to the world as Superboy. I spent about a decade based there, performing good deeds and super-feats at home and abroad, and then moved my focus to a city called Metropolis a few years ago, where I've been operating as Superman.
"The press has always interested in me, of course, and I've told them just what I'm telling you now, but Earth has had its share of heroes and villains, people with remarkable abilities, and even with people from other worlds -- I was unique, I think, but not unprecedented. I've visited alternate Earths, sometimes ones where I didn't exist, but as often as not they were similar enough to my own world that I didn't realize what had happened until well into the visit, sometimes after I left. Not always, though. I think that may be what's happened here."