Person, persons, people
One human is a person. The plural form of person is people. Some people say "persons", but that is wrong and those people are stupid. Lawyers are not stupid, usually, but they like to say "persons" because they like being different. Lawyers have their own language, called "legalese". Legalese is like Elvish. Both of these languages borrow heavily from Latin and only exist in imaginary worlds. Humans speak about people. (Don't ever use legal documents like laws or contracts as examples of good English.

Exercise 1 - Put one of these words into the correct space (you won't need one of them): person, people, persons
A. Jim is a tall _____________.
B. I've met a lot of _____________ in my life.

Sometimes we generalize about people who are members of a group. For example, in the first paragraph I referred to "lawyers". There is no need to add any more words after "lawyers". We know that we are talking about people who work in the field of law, and, therefore, there is no need to say "teacher people" or "plumber humans". These examples refer to people who have similar jobs, but it works for any group. For example, we may speak of "South Africans," "Christians," or "gamers."

In some cases, when the collective noun sounds funny, we add "the" before the word. Some examples include "the Chinese," "the French," and "the Japanese". We use these versions when making very general statements, like "The Chinese eat less fish than the Japanese." This sentence is basically the same as saying "Chinese people eat less fish than Japanese people."