I'm only referring the ability to do something. I don't get into genetics until things turn into "best prefomance" that's when average people get weeded out and genetics becoming increasingly important. Anyone can compete in swimming but there's a natural build and genetics when it comes tobeing among the best. It is what it is. At most, many people are going to be good at things. There are very few people that I met who couldn't overcome horrible. But being the best is as you state, lots to do with genetics.
Sorry, I missed this post earlier. I wasn't ignoring your response!
I feel that you aren't just talking about "best performance", you're also talking about appearance too and using it for a metric for how well someone is training, without considering the large role that genetics play in how people look and how their bodies respond to stimulus. You also seem to be ignoring the fact that genetics play a significant role in aptitude and that aptitude impacts participation at most every level and participation shapes what we think a participant in a particular sport should look like.
People who have bodies that are ill suited to an activity tend self select out of those activities and gravitate towards activities to which their physique is more suited. I'm talking populations here, not individuals, there are plenty of short people who love and play basketball and skinny, more fragile, people who play football, but they tend to be the exceptions.
For example, I have really short legs and a really tall torso. I
hate long distance running. It is just about the most miserable activity that I can imagine. My short legs have to carry my big, heavy, upper body around and I have to take like 3 strides for every 2 of other guys my height. Sprinting I've always enjoyed, because even as a little kid I've always carried a lot of muscle on my legs and I could run short distances faster than my classmates. So, I did track and field in school, but I was never any good at any distance longer than 100 meters. I could accelerate quickly but there was a low limit on my top speed, like pedaling along on a bike in first gear.
Even at 100 meters, my short legs limited my abilities. I was the fastest boy in my elementary school, but I was middle of the pack among the much larger pool of competition in high school even though I put in as much or more effort than the average while getting the same coaching. I wouldn't call high school "best performance" or "world class", but my genetics definitely meant that I wasn't going to be taking first in the 100 meter at my high school, much less at the intramural or state level. And while short, my legs aren't freakishly short. People don't stare at them or make comments. They're just shorter than average enough to place an upper limit on my performance.
It's a chicken and the egg thing. Do sprinters, as a population, look like sprinters because they sprint, or do they sprint because they look like sprinters? I sprinted because I looked like a sprinter. Of course the more I sprinted, the more I looked like a sprinter, and my legs probably would have atrophied somewhat if I'd switched to running marathons, but I'd still have looked like a sprinter (with short, muscular, legs) trying to run a marathon. Can you find guys built like me running marathons who train exclusively and effectively for marathons? Sure, and some of them are pretty good, but not a lot of them are coming in first, even at small, local events.
Was it a waste of time to compete in the 100m dash, since I wasn't going to be successful in anything but the lowest level of competition? I guess it depends on your values. I had fun with it, and having trained in sprinting, though slow in comparison to a lot of other sprinters, I was still much faster than people who didn't have any training. Having grown up in a very violent time and place, this skill saved me from serious injury a couple of times too, so it did have some practical value as well.