What do you think when these words come up: "populace", "population", "people", the "mass", the "public"

My question: Is it true that the Populace brings negative connotation and nuance when used compared to the Population which both refers to the People lives in a particular place?

"Populace" is quite condescendent (showing that you believe you are more intelligent or better than others) and refers to the lower class by opposition to the elite.

"Population" has an administrative or social connotation and refers to persons living in a specific place (city, country) or belonging to particular catégories, e.g. farm population, foreign workers population.

What about if we want to convey the meaning of each person in a people' community? What word would you use?

You may refer to a "community member" or use words depending on the type of community:

• for a city or a state: citizen,
• for a religion: coreligionist,
• for a company: coleague,
• ...

Mass

Besides belonging to "mass media" expression, "mass" is often used in a political context to evoke the majority of the population (mainly working classes and poor people).

Example: Mass culture is the set of ideas and values that develop from a common exposure to the same media, news sources, music, and art. Mass culture is broadcast or otherwise distributed to individuals instead of arising from their day-to-day interactions with each other. Thus, mass culture generally lacks the unique content of local communities and regional cultures.

Public

The noun "public" is generally used when people is the target of something or someone, e.g. news, discurse, artist performance, opening hours of a place or a service, ... .

Public is often a synonym of audience, e.g. for a speech, a show or a TV programm.

Example: The Championship was followed by a public of wrestling connoisseurs and fanatics.