Also it really depends how big the talent gap is between individuals, how early they start, and how much and how good their instruction is.
Talent in riding encompasses having a certain body type (long legs), certain physical abilities (balance and timing), but also certain mental or emotional abilities like empathy for the horse, an ability to teach an animal something , and relative fearlessness. And a strong desire to ride.
Out of any two beginning riders, one will always seem more talented compared to the other but the advantage might be minor, and the relative rankings reversed within two years.
Or one rider might seem talented because they are being compared to someone who is a real klutz.
Malcolm Gladwells “Outliers” was useful in pointing out that early intense experience often creates the expertise that is later seen as talent.
With riding, bad instruction can mess up a young riders seat over time, or deaden their natural feel for a horse.
Anyhow, I had “talent” in a couple of nonsport areas as a kid, one area of which I professionalized, the other I stayed very amateur. I had to work at my riding and overcome some fear, but after 5 years I was riding very well for my time and place. As an adult returning rider I feel it took almost ten years to get back to that level of comfort (which is in line with Gladwells 10,000 hours).
Both my areas of talent as a child were jump-started by parents encouraging me very early. Nevertheless to professionalize in one area still took enormous effort and even so, I am not at the top of my field, just middling (and thrilled with that).
I’d say that talent is just the starting point, and it can even make you a bit lazy if you expect and want everything to come easily. Indeed, it was riding that taught me that you can learn and improve and surpass others, that raw talent isn’t the whole thing by any means.