Is it true that most coworkers don’t care about you and only themselves?

Every time I be polite and say good morning, I either get ignored (no response) or people give me a dull “hi”. They act excited when they see the kids.

I feel like some people don’t like me too much. I mean I’m polite and greet them but they don’t get excited when they see me.
When I said hi to some of the staff, they ignored me and said hi to the students. I understand students need more attention than us but a simple hi would be nice.

When I complained about a kid not listening, I got ignored. One shrugged her shoulders and said it’s my student and she has her own problems. I got no help when I was struggling.