Why is 'it' a personal pronoun?

Answer 1

I, you, he, she, it, we and they are the subject personal pronouns used in English. They are used to substitute the names of the people or things that perform actions. In English, we make no distinction between singular and plural forms of "you".
This is why 'it' is a personal pronoun and this is the rule. It can be used to replace a person who's gender is not known. This is often used with babies when the gender isn't known. For example, "Is it a boy or a girl?" It is generally frowned upon when talking to adults because it has a tendency to be dehumanizing because it is also used for inanimate objects.

It can also be an impersonal pronoun as in, "It is a nice day," or, "it seems to me that people should be nice to each other."

Answer 2

'It' is considered a personal pronoun because it can represent a person, animal, or thing being discussed. It functions as the subject or object of a sentence, replacing a noun to avoid repetition and add clarity to the sentence.