Oh that makes sense, sorry I misunderstood!

Yep, they/them/theirs is used in the same place as he/him/his or she/her/hers. It/it/its should not be used for people unless someone explicitly says those are their preferred pronouns. "It" is typically used for objects and non-human animals, so it could be seen as rude to refer to a human as "it." If unsure, use they/them.