I have ridden thoroughbreds — not racing of course, but just to knock around polo balls with friends. They are huge and powerful animals. I’m amazed they let me on their backs at all.
I ride racehorses, you are not just along for the ride. A good jockey needs to rate a horse. You can’t hold back a thoroughbred without having the strength. I’m a women but not a jockey. I’ve had a few women jockeys but would never have one in a race this big.