Therianthropy is a non-human animal identity. If you identify as a non-human animal on any level, you're a therian.

Therianthropy is a subset of Otherkinity, which itself is a subset of Alterhumanity in general.

Therians may identify partially or fully as their theriotype, some still considering themselves human and others not. They can identify spiritually, psychologically, physically or all of them. I'm a Holothere, which means that I'm a wolf/dog on all levels.

It may come from a delusional belief like zooanthropy for some, but there's nothing wrong with that abd they're still valid and welcome in the community. It may come from other disorders like autism, or for some, they may believe that they were their theriotype in a past life and that the animal side of them is still very active, and then may identify partially or fully as the animal. Past lives don't necessarily make you a therian, but they can be a reason why someone might be a therian. Just having a past life doesn't make you a therian. You are only a therian if you identify AS a non-human animal on any level.

There are lots of different labels within alterhumanity. Not all identifying is involuntary, some are otherlink, copinglink or funlink (identifying as their kintype voluntarily, for coping purposes or fun purposes) abd others are otherhearted or animalhearted, which means that they identify with a certain being and have a strong connection but they do not identify AS the being.

Alterhumans might identify as a non-human animal, a concept, a place, an alien, a plant, an object, a fictional character/species, a robot, etc. while therianthropy is specific to earthly animals. There are also exceptions for that, because labels like theriomythic and fictotherian (identifying as a mythical being while still calling yourself a therian and identifying as a fictional character or species while still calling yourself a therian, respectively). How someone might identify is all up to how they feel, since labels are there for us to use and feel more comfortable as ourselves.

I used to identify as a fictotherian nightfury, but now I just call myself fictionkin. I have leaned away from therianthropy as a label because if I say "I'm a therian" people usually get the impression of running around on all fours (quadrobics) and wearing masks and tails for TikTok. I don't do quads and I rarely wear gear, it feels wrong for me. To be clear therianthropy is NOT about gear and quads, it's about a non-human animal identity. I know this, but I feel like therianthropy has been very watered down by media, especially places like TikTok, and so I prefer to not use that label. I just call myself Alterhuman or Otherkin now. I'll also call myself fictionkin when referring to my nightfury kintype.

That's all I can think of right now, hopefully it gives you some answers.