it doesn't have to be.
https://en.oxforddictionaries.com/definition/person see 1.1
It can be anything that seperates them as an individual.
it can be via there name. an id. location data OR an online identifier. if that information can be tracked to an Individual indentifer it is personal data.
Your Character for example can be identified as an individual person or player. while people may not know your real name or address or anything like that. your character is still an online indentifier and can be indentified as a person. not a group of people but an individual person. and that makes any data pertaining to your online identifier. personal data.
The Lodestone is directly connected to the game and thus you consent to it having that data when you accept the terms and conditions for the game
you can however go into your lodestone and choose what data you wish to share. you can hide your achievements your friends, your minion collection and various other things.