Hi and welcome to PC!
I am sorry you are feeling so down on yourself.

I can relate. I'd felt like a huge loser in high school. I honestly am not very creative and have few talents. I am gifted in some areas though. I just tend to not see this unless someone points it out to me.
Maybe make a list of things you do like about yourself?
I like Farrhaige's comment re: seeing a school counselor. Is this a possibility for you? A high school counselor helped me a lot back when I was struggling in my teens.
I hope you will keep posting so we will get to know you and can support you.

WC