1. you don't have to understand it, you just shouldn't be a legislative genocidal asshole about it (not that that's what you're doing, but that's what republicans seem to do to anything they think isn't their slim sliver of a definition of "normal")

2. if you're talking about furries, to my layman's understanding of the subculture, that's not how the vast majority of furries relate to themselves. From what I've seen, it's not that they are the animal itself, they are the aspects of the animal, and those things are just little icons that they're like boosting because they resonate with it. That said, there are at least a few people who DO feel that way, but I'm pretty sure they have a special category name (ferals? I think that's what they're called but I could be wrong, this is some deep lore I picked up years ago). If they do have that special name and I'm not just making that part up, then that implies that most furries do not feel that way about themselves.

But, acknowledging the existence of people like that at all does validate your question in my mind. I don't really understand that extreme either. My only point is that most furries are what you would likely consider "normal", they just have a particular hobby. It's no more nefarious or odd than being into gender bending cosplay. You're just taking something (yourself rather than an anime/video game character) and twisting it into something artistically different (a fursona instead of a cosplay outfit).

....no I did not intend to write that much defending furries but here we are lmao