There is a concept of 'product-market fit'. If you google for it, you'll get a bunch of buzz-word filled blogs from venture capitalists, but it basically means your product meeting some demand within a market.
That market doesn't necessarily have to have competitors in it, but if it does, you have to say how your product will differ, how it will 'better fit' the needs of the market etc.
In your case, it is just about thinking what sort of person is going to read your book and why. A useful exercise marketing people do is dream up an imaginary 'typical user' of their product:
"Thomas is 35, urban professional, married, no kids. Travels to work in the city by train during rush hour, and prefers to read the paper in the mornings if it isn't so crowded that he can't even get the damn thing open without poking someone's eye out. Otherwise, will read or play games on an ipad on the evening commute home.
"Thomas feels the 'hero' role is staid and overdone, having seen too many hollywood comic book film adaptations, and is looking for a good anti-hero to balance. Likewise, his office-drone-worker job makes him yearn for an everyman he can sympathyse with"
etc etc
Of course, this is just to visualise and humanise otherwise bland statistics about the 'target demographic'.
Also isn't it quite dangerous reading something a bit too close to your own writing as you may find yourself subconsciously immitating it?
Edit: I wouldn't talk to a publisher about any of this stuff as you're basically second guessing them / trying to do their job for them and they're almost certainly better at it than you. You don't necessarily have to think of a 'typical reader' or the sort of person who would enjoy your book in marketing terms and marketing speak either, just have an idea of who, aside from you / 'people like me', would read it
...that's a bit behind the times. I hope they don't expect me to print out the entire manuscript if they request a full. that's like $100 to print.
