While Lexis publishes many articles that are useful to lawyers, reading them without a legal education can result in misunderstandings such as yours.

The numerosity requirement means that there are so many members of the class that each one bringing a separate lawsuit is impractical. It does not mean that you need 100 plaintiffs or, indeed, any minimum number.

What you do need in a class action is one or more people who will be representative plaintiffs whom the court believes will *adequately and fairly protect the interests of the class."

That's why the caption in a class action usually reads something like, John Doe, on behalf of himself and all persons similarly situated v. Big Company, Inc. There will then be a section of the complaint that defines the class, e.g. "The class consists of all persons who purchased the defendant's product called Better Widget between January 1, 2022 and its removal from the market on October 2, 2022."

Incidentally, the document you cited refers to the federal rules for bringing a class action in federal court. Class actions can also, in some cases, be brought in New York State courts. See CPLR Section 901 for the basic rule.