Stoner by John Williams. It is a slow burner, but it’s worth the effort. It’s novel about an average person living an average life, but the prose captures the emotion of life.
No need to apologize. You were right in one way. It was an unknown book for many years until it somehow got rediscovered and turned into what many regard as a classic.
https://en.m.wikipedia.org/wiki/Stoner_(novel)