For context

I have heard my fair share of tall tales of how someone went up for their military service and they got noticed as a good shooter and got sent or at least invited to join the marksman course.

My question

But what I would like to know is if someone, let's say in their late twenties to mid thirties was to be forced by some event of their life to pick up shooting as a means of survival, like hunting, would it be possible for that person to become a better than average shooter, admiting they had the time and resources to practice.

I am aware some individuals may have knack for some activity or skill or something alike it but shooting, in my understanding, is more about early introduction and constant practice than just inate skill.