One of the things that you hear a lot is that most folks' first novels are autobiographical to some extent (sometimes to a larger extent than others). I can sort of understand why this would be the case: after all, the old axiom is to "write what you know," and the one thing that folks should know better than anything else is themselves (in an ideal world, at any rate).
I'm looking at my own novel, now, and I'm glad that it's not very autobiographical at all, because that would bear with it the implication that some truly horrible things have happened in my life, both to me and the people I care about. I'm pretty sure, though, that such a text couldn't ever really be mistaken for autobiographical, in this case, first novel or not.
I was thinking about the whole "write what you know" thing, and when I looked at my novel-in-progress, I started wondering to myself where I got off on attempting to write about things that I certainly hadn't ever experienced myself (like getting involved with government conspiracies or living the life of a billionaire).
When I looked more closely, though, I realized that the things that really held the book together from an emotional point of view (or which, in theory, should hold it together), are themes that I can certainly identify with very closely, like friendship and social acceptance and self-sacrifice. I'd also like to think that readers would be able identify with that, too, and maybe, in a way, that's where the 'meat' of the story comes, in terms of what's thought-provoking and what leaves an impression.
Besides, if we're going to limit ourselves only to things that we know, thennobody would be writing books with gun-toting animal-people having a helicopter chase.