To reach the very top of the heap in just about any endeavor (Olympic gold medalist, UFC champion, etc) you need just about everything going for you - natural ability, insane work ethic, starting young, first-rate coaching, and a bit of luck. Most of us will never come anywhere close to that.
The good news is that you can still get very, very good at something and get lots of practical benefit from it without being one of the best in the entire world. The vast majority of martial artists will never reach even 50% of what they are genetically capable of, so there's not much point in worrying about how much your natural ability might be holding you back. You can always get better. You just have to look at how much a given amount of progress is worth to you in terms of time and energy and decide how much you want to invest in your training versus using in some other area of your life.
I am myself on the low end of the bell curve in terms of natural ability for the martial arts. I started out uncoordinated, out of shape, inflexible, non-aggressive, and shy of physical contact. After 37 years of training, I'm an above average martial artist and instructor. I've seen lots of people come in to training along the way who were way more talented than I am. They started out better and progressed faster. Most of them dropped out along the way. I kept going and kept progressing. If I put more daily time and work into my training, I would progress faster. I don't think I have the capacity to become a world champion at this point, even if I trained as hard as I could, but that's okay. There's lots to achieve without going that far.