I think I'm a decent person. Shouldn't the other person know if they'll like me or not?
But you said:
I don't know know why anyone should like me.
You have to like yourself first. If YOU don't like yourself, then why would anyone else? You have to realize that people can pick up on whether you like yourself or not. Little things like body language or word choice or eye contact speak volumes.
Being a "decent person" is good, but why do you think that's enough? You SHOULD be a decent person, regardless of whether or not anyone likes you.
You have said multiple times you don't want someone to "settle" for you, yet at the same time don't feel inclined to do anything to make yourself better or stand out from the crowd.
This comment here says a lot:
I do like myself, I just don't think there's anything special, unique, etc. about me. I'm pretty plain looking and boring.
As the other guy said, would YOU hang out with yourself? If you were a guy, would YOU want to spend time with you or sleep with you? Remember how I asked earlier if you want to be liked or sexually desired? Well, being a "decent person" may not make people hate you, but it's hardly going to make people cross oceans to be with you.
There's a billion billion people out there. You have to be BETTER than them if you want people to spend their precious time on you and not them.
Come on, you have to put EFFORT in.
Again, I'm ugly as hell, but you know what I do to compensate? I try and make people feel better about themselves when I spend time with them. I compliment, tease, crack jokes and make people have FUN. So you have to improve yourself to compensate for any deficits you think you have, i.e. being "plain" or "boring."
If you wouldn't hang out with yourself, then you need to change that. No one else can.