These are the demonstrative adjectives, which means they need to precede a noun. However in a Grammar book of mine, it says that they can only define people such as ''ano hito was....'' yet I've often seen them used with animals/objects as well. For animals/things the same book clarifies that only the pronouns kore/sore/are are used.
Can someone explain it to me?
That book is wrong. They can all be used for people, animals, objects, etc. In other words, they're used before nouns. Here's a decent overview I found: https://www.thoughtco.com/ko-so-a-do-system-2027822