Why are people not interested in talking to me?

I am, look, I just did!

Here is a generic link of possibilities.
https://www.inc.com/kevin-daum/17-reasons-people-aren-t-listening-to-you.html

Also consider that these are not the right groups for you?
( some groups are immature and still behave as if in Junior high school).
As long as you are kind, considerate,listen well, and don’t add negative comments you will do fine.

Sometimes its not just you, but others that are intimidated, envious or just have other more important priorities on there minds.

Are you a boy or a girl? Do you always talk about others or just yourself? Do you hog the conversation? Are you highly critical of others? Do you ever compliment others?
Try listening more, and taking interest in what others are talking about, then talk about what they are talking about, or what their interests are.

Do you have Resting Bitch Face? It’s a real thing.

Are you beautiful? Do you make eye contact? Are you smiling during your interactions?

Maybe ask your close friends. You’ll get better feedback from them than from people on the internet who don’t know you.

There can be advantages to going unnoticed. If you have a talent for it, perhaps you should exploit it.

Do you smile even when there is nothing to smile about?

Conversation is like a bird in flight. It wants a safe place to land. Smiles are a safe place to send a conversation.
If it doesn’t come natural to you, invent smiles. Look at someone you wish would say hi. Picture them as having sharpie doodles all over their face, with colors, and bugs, and flowers. As soon as they notice you, beat them to it. Say hi. The amusement will come across in your voice, and their conversation will have a place to go.

@Patty_Melt Such pretty words, anyone could tell you are a writer, my friend. (sigh)

Can you carry on a conversation with another person when you two are alone? I will assume “Yes”. .
Does the problem occur only when you are in a group? Again, I will assume, “Yes”.
I know this sounds strange but you might be too polite. You might be waiting a fraction of a second too long after the other person finishes speaking before you start. Others might assume you have nothing to add and then they start.
Try an experiment. Butt in immediately after the other person finishes speaking or even before. It will seem rude but watch and see how others do it. It can be a cultural thing.

If none of that works, try going out in smaller groups. The conversation is way better.