I think overall they are pretty good. It’s hard to take good horse pics because you have to get the timing just right on the shutter. If you are having trouble shooting above 400 ISO with your body you will definitely need to find a newer one or deal with more noise though, KWIM?
I’ve noticed a lot of people take horse pictures with too short of focal lengths but you don’t so all the horses actually have butts in proportion to your heads. I’m not a huge fan of suspension shots in the canter/ gallop, I like the look of the 2nd beat more right before the inside front hits the ground and the first beat isn’t really as good a way to show the horse when they start to reach under themselves just because it sort of makes their butts look funny.
The photo that I notice the softness in the most is the one where you have the gray landing after the white/ green vertical. There is also the jockey with his skull hat cut off and the others that CC mentioned.
The photo with the baby bothers me the most because it scares the begessies out of me just because it isn’t a safe thing to do at all and although I do see it time and time again from other horsie friends you should never risk the safety of a child for this photo IMO. The only way you could do this photo safely is as a composite. I don’t care how bombproof a horse is, horses are unpredictable by nature and their forward eyesight is poor and they have trouble seeing little kids. Once the horse picks his head up even just a little higher he won’t be able to see that baby there at all, KWIM? (It also looks like there are horse apples next to the kid but that bugs me less than the safety aspect).
Are you planning on catering just toward jumpers/ race track crowds or dressage as well? Dressage riders will want to see trot and lateral work as well 🙂
ETA: Cameraclicker’s comment about shooting raw will help a lot with noise/ blur. If you do get stuck shooting a step or two underexposed to stop the motion you will be able to fix it a lot easier in raw than in jpeg with less noise.