这个is incompatible with a plural. so 这个人们 is not correct. There is a measure word for plurals: 这些人。It is obvious that this means several people, so you wouldn't add 们 to make the plural. Plurals are only used in Chinese when they are essential for understanding the sentence, and nothing else in the sentence gives the idea that the noun is plural. (You can usually get by quite well in Chinese without using any plurals at all!)

Hello Ali, "个“is usually used for singular words, while "些" is used for plural words. So instead of saying "这个人们" or "那个人们", it would be more suitable to say "这些人们” or “那些人们”。 Good luck! Axlent Tutor from Italki

这个 means this 那个 means that 这些 means these 那些 means those because 人们 is more than one person,so we dont use this and that.we can use these and those.so 这些人们 and 那些人们 is correct