Levistus's_Leviathan
5e Freelancer
I wasn't asked before, so no need to be snarky.That's a cop out. I made a stab at who they were, why won't you?
A person is an individual who has enough intelligence to have a culture (sometimes religion), develop tools and creative problem solving, self awareness, and is fit to be a member of society.
Intelligence is a requirement, but it doesn't give you innate personhood. Culture is key, without culture we wouldn't be people. Development of tools is important, and is what was a major drive in the evolution of humans as we know them today. Self-awareness is very important "I think, therefore I am". You cannot be considered a person if you cannot see that you have a purpose above being a member of a community. Creative problem solving is important, and is what gave us our creativity and tactics that make us human.
The last part, "is fit to be a member of society" is important, perhaps the most important. You have to understand other people's needs, the benefits of being in a society besides the sole benefits to yourself. You have to care about other people.
By my definition, the standard Mind Flayer isn't a person, as their diet requires them to not be able to be a fit member of society. By my definition, murderhobos, liches, and serial killers aren't people.
By my definition, gorrilas or chimpanzees, who are intelligent enough to learn language, communicate, and be in society, aren't people. They don't develop culture or religion.
This is my definition of person. You are born a person, but can choose to not be one. You can be born not a person, but choose to become one.