make sure you are set up with junior gears (I think it's 52x14) - 26' rollout.
training is really important to develop into a quality racer.
if you can join a junior-focused team/club with a good coach, it will help you grow instead of burning out.
Forget any talk about genetics and what you are born with. That, to me, is just excuses.
The real challenge is to build your strength from season to season and learn how to race.
I've seen many quality juniors that simply burnout by the time they hit cat 1/2.
Anyone starting from 15 yrs old can become a quality 1/2 racer. For now, I would really focus on having fun and joining a club.
You can learn a lot from them.
good luck!