People evolve, why not your characters? My lead actually wants to go the other way. He's a hero, but would much rather be a farmboy. It's a valid concern, it happened to me. I saw people waste their existence (pardon the mix of metaphors) chasing windmills. Your character might have the same perspective. He sees a family/lineage in crisis, or he wants more than the family's 40 acres and a mule, or there's a need in society that he feels goes beyong the idea of self.
If you are going to use the old, overused farmboy-to-hero story arc (Star Wars, Superman, others), then you should at least try make it interesting. What does farmboy actually do on the farm, aside from tending to cows or crops? What is his inner (emotional) life like? What does he dream about? Is he happy with life on the farm, or does he dream of going elsewhere and doing other things? Does he leave the farm because he wants to, or because some other character, event or opportunity lures him away? What precisely about farmboy, what special trait or ability, gives him the means to become a hero?
It's the exact plot of Superman, so perhaps a little cliched. You could extrapolate the key points and transpose them onto another scenario such as a city kid, or so fourth.
It's a little cliche'd but if you write it and people like it then I don't think that that will be the main concern of readers
Insinuating that the overuse of this plot structure somehow degrades the power of your work is arrogant. You're implying your work is legitimate and will actually have an impact on readers.
