What if you are unable to learn?

I'm fascinated with the idea to learn coding and become a software developer. But my brain can't seem to be able to do it, no matter how hard I try (I even pay for courses and for someone to help me). I've tried for like 5 years. I work in a restaurant now (but somehow I could learn what needs to be done) I'm not 21 yet so I still have time, but what if my brain can't code? How to find a job that pays if I can't do it?