people is a singular noun, just like person is a plural noun. We always use "person" as "one person, two persons", rarely use "people" as "two peoples". But actually ,the use of "several peoples " exists.

I can not think of a situtation were the word "people" would be treated grammatically as singular. As far as I can imagine, it is treated as plural. People sing People run People are The singular form would be "person" The/A person sings/runs/is It can be used as a collective noun to describe a group of individuals joined by a common denominator (e.g. country or from a region) but it is still treated in a sentence as a plural word. Examples: The people of Spain ARE nice. People ARE generally hospitable in this region. The people ARE not pleased with your decision. The word "peoples" also exists although you are less likely to encounter it. It is used to describe several groups of people joined by a commonality or common community. e.g. "Indigenous peoples" (the are all indigenous). examples sentence: Some people think (plural form of the verb) that the Indigenous peoples of Brazil are under threat due to deforestation and globalisation. You would very rarely need to use the form "peoples".

"People" is in origin a noun referring to a population group (like "pueblo" in Spanish which has the same origin) and is singular, with its own plural form: "peoples". E.g. the peoples of the world, indigenous peoples, People's Republic of China. However, due to similarities in meaning, it has come to be (more commonly) used as the plural for the unrelated word "person" (which also has the plural form "persons", now largely restricted to technical and formal use). In this sense it is logically treated as plural. Therefore, "people" can be singular or plural depending on the context, but in most everyday circumstances, including your example, it is plural.

Well you don't use the "s" because is plural, you use the “s" in the singular of present with he, she or it for example. He plays She plays In the case of: we, they and you, don’t work of the same form for example. You play We play They play You can considerer people like we or they

In some scholar journals you will find individuals who insist that the word "people" is singular when referring to a specific group. I challenged one of those scholars but discovered later that my mother grew up using a textbook he had written decades before. in his presence, I was forced to use people as a singular noun.