If I had to choose a Great American Novel, it would be either “Huck Finn” (rural, poor, doing the right thing despite mores and one’s own inclinations) or “Gatsby” (urban, rich, remaking oneself to fit a dream). Both speak the American vernacular. Both are in the first person. Maybe the Great American Novel has to be in the first person because we are.
Pick up “Gatsby” and read that first page. It'll be 100 years old in 2025 and it sounds like today.