What makes a person indigenous in a worldwide context?

For reference I’m mixed race and Nigerian on my dad’s side, Dutch on my mothers. I want to be clear that I’m not one of those conspiracy theorists that make unbated claims about other races being the original everything, I just want to gain some perspective. I want to know why we use certain language around different cultures differently. For example, Native Americans are indigenous and there are many different tribes. The exact same thing can be said for Africans but you never hear them be spoken about as indigenous. I want to know why sociolinguistically, or if I’m incorrect in seeing it as so. If anyone has any resources or books about this I would appreciate it a lot :D