
That's what people do. It's how we identify and relate to one another. It's not like you can just NOT label things, our whole brains are programmed to find patterns efficiently.
It's not like you can have a conversation like "Hello! What do you do for a living?" "Oh, I work." "Oh I too work for a living! We are normal humans aren't we?" "Yes we are.".
Instead we divide and label and then define some more, because that's just kind of how language works. It's a balance between strict definitions and evolution of language that makes it so when I say "I'm bi, I'm a dom, I'm a drag queen" or even "I'm a farmer" or "I've got a wife" or "I love God" we know what the other person is saying and how it relates to us. And leaving things unlabeled makes it harder to relate to one another. If I don't say "I'm bi and poly" you would never know if I'm someone whose life experiences you could relate to, or if you're attracted to me you could never know if there's even a chance I could be attracted back, or even if I'm someone you want to be friends with because your religion forbids it.
For that matter, a lack of labels tends to cover up the existence of minorities and make it harder for them to relate to one another. It's easy to say "intersex people are just a rare anomaly" when you don't know that 2 out of every 100 people are intersex. And we can't know how many there are if we don't define it somehow. Gay marriage wouldn't be a thing if a lot of people hadn't been able to stand up and say "I'm gay". The recent court decision protecting our right to not get fired couldn't exist without defining who we are.
We wouldn't get very far without labels for things, as confining as they can be sometimes. The nice thing is, though, we can always change our mind, make new labels, or change old ones if we need to.