How would one say in Polish "good peoples" when referring to different sets of people. I guess the Italian la gente, la persona, le persone, il populo, and i populi are tweaking my learning. Then we have the American statement: "He is good people." I wonder how that would be translated into Polish?
I'm not sure what you mean by "different sets of people". Good peoples only refers to different nationalities/ethnicities and is therefore a morally highly questionable statement.
Regarding "he's good people", I'm convinced that people can be replaced by a person. That would convert it to standard English, without changing the meaning.