Both mean people/peoples. Is 民 is for plural connotations? For example: 住人 means “dweller; resident,; inhabitant” and 住民 means “citizens; inhabitants; residents; population”, according to Jisho.
民 is more of a collective noun: “The indigenous peoples of Australia” or “Slavic-speaking peoples.” It’s used for ideas like nationalities or ethnicities.
人 is more for referring to actual concrete people that you can see like “There are many people in this elevator” or “I have three people in my English class.”
From The Key to Kanji:
“人 depicts a person standing upright.” So it means person or persons. A collection of individuals.
“The ancient form of 民 depicted an eye pierced with a needle to make someone blind, symbolizing someone who must do things against his or her will. It indicated “ordinary people” who do not see things or express their own judgment or view under a ruler. Now the kanji 民 just means “people”.”
So this one had the connotation of subjects, and represents something like a class of people, like a group of people who reside somewhere (as a group).
That is the original character, but the second half seems to be a bit much pontification. Anyway, that was all well before it came to Japan. I don’t think it’s ever meant anything but “peoples” in Japanese.
It explains some compounds that were formed previously. It has a “folk” connotation, like 民話, 民俗, maybe even 民主. Connotation != meaning, obviously.
It definitely has a folk connotation. I guess the part that seems odd is that things like education and that kinda critical thinking just didn’t occur among the lower classes back in those days. But then again I don’t know when exactly those words were formed, or really enough about Chinese history.