I get and read an enormous number of first novels.
Knowing and knowing what to do about it were two different things.
You use simple brushstrokes in a screenplay for things over which you would take much greater pains in a novel.
Cary Grant never won an Oscar, primarily, I suspect, because he made everything look so effortless. Why reward someone for having fun, for being charming?
Ultimately, your theme will find you. You don't have to go looking for it.
I don't think America has ever had a center the way London is the center of England or Dublin is the center of Ireland.