I beat Arcanum a couple days ago and was thinking about the story when it occurred to me that I didn't even know who I was (the PC that is). I'm 35 years old in the game, so what did I do with those years prior to the blimp crash. Also, why was I even on that blimp? It is all too likely that I missed or forgot this information during my play through. Any thoughts?

If you check your journal - you will see it says that you suppose that you just survived the crash. I think you rose from the fire as the legend says as the "Living One" You were not on the blimp. You merely thought so.

Well that is sort of why you are given the option during character creation of having a background story. If you did not take one of the backgrounds offered, then it is assumed you were pretty non-descript. As for the reason you were on the zeppelin, maybe you were on vacation. But if you listen to and believe Virgil it is just like Lou said and you are the avatar of his god who came down from the heavens to fight evil.

Just as in a traditional (non C)RPG it is your task to decide what role you play. You make up the character, the character's motivations, background/history and psychology. Arcanum manages that aspect better than Fallout, imo, as your role in the world of Fallout (Vault Dweller) is much more prescriptive from the start.

Some of the pre-made character backgrounds would seem to contradict that, but it WOULD explain why no matter where you go, nobody knows who you are without an introduction. By default, you are a nobody from nowhere that just happened to survive a blimp crash.
I think that, if your character is to have any definite past or personality, it must exist purely in the mind of the player. Your character might have a meta-existence, but there really doesn't seem to be one that's written into the game for you.

Hmm, all interesting ideas. Perhaps in becoming the "living one" I lost all my memories of people (and they me) and places in Arcanum. Thanks for the feedback.