You might not consciously pick a theme for a story that you’ve written, but it’s still in there. That’s because a book’s theme is tied in with your basic story as well as from your characters.
Pitching your MS to literary agents is 1) super scary 2) depressing and demoralising 3) taking waaaay too long 4) all of the above.
It can take a long time to crank out an eighty thousand word novel. Your chosen path to publication can increase that time significantly.