Why do I feel that I am rejected or neglected by people?

This could mean you are distancing yourself from others or feel like they are doing this to you. You should consider talking to those who are close to you and try to figure out a solution that works best for you.

You don't pay enough attention to what people say to you, but people are usually busy with their lives and that's totally okay, try to find some new friends that would not ignore you in any type of way, i hope i helped :)

You may feel this way because of how other people treat others in comparison to you it's important to understand that before someone gets to know you you may feel neglected or rejected

It may be just self doubt, which is totally normal. It's hard to accept love from others when you feel like you don't deserve it.

Have you looked in the mirror lately to see how beautiful you are? Maybe you can start by not neglecting or rejecting yourself first? Have you ever practiced self love?

Building up the courage to talk to someone only to have them exchange a few words then walk away makes me feel rejected and as if I'm not good enough to talk or become friends with anyone else in my class, or school.

self belief or self worth could be low speak to someone or get advice from councellors or therapists or even family members

This is probably a fear that comes from our deepest scars from childhood. We tend to have a terrible fear on being alone and not wanted. We need to mend those deep feelings, and then sharing with people will be so much easier.

I think you are looking too much at outsiders for a barometer on how you are feeling. If your focus is on making yourself happy and responsible for your happiness you won't feel neglected or rejected.

Because the attention you provide isn't reciprocated by people. Generally we expect that if you helping someone in their need, they will also help you in your need. It's the expectation we all have. But when such event not take place and it remains one-sided only, then it feels rejected and neglected by others. To avoid it, accept the fact that you can't control other's thoughts and actions but you can guide yours. So, try to do what seems best to you!