What's the meaning of this sentence?

“Knowing no more of Mencken than I did at that moment,I felt a vague sympathy for him.Had not the South, which had assigned me the role of a non-man, cast at him its hardest words?”
This sentence is from “Black Boy” by Richard Wright.

“Had not the South, which had assigned me the role of a non-man, cast at him
its hardest words?” what’s the meaning of this sentence? What’s the meaning of “non-man”?