What preditor was so fast horses had to evolve to that extent??

Same for rabbits. The are basically as much lean muscle that can fit on the lighest possible skeleton.

If you pick up a rabbit wrong, they can snap their own back with the momentum from kicking their back legs.

I did this too and will also never own a horse lmao. This is why horse people are weird.

Basically a 900LB Cocker Spaniel that's afraid of it's own farts and will eventually kill every single tree within reach. I also will never own horses.

To add on why broken legs are fatal: its because horses are so big, that even with a sling, they cannot support themselves well on 3 legs. And lying down is also not an option as their own weight will crush their internal organs if they stay down for too long.

From what i read here there's no unhealthy horse, it's either healthy or dead.

And they run around at 60mph on the tips of their toenails.

That’s completely untrue.

Evolution applies to the entire lifespan — if we could “reproduce” but died in childbirth every time, our species would have gone extinct long ago.

Parents and grandparents also contribute greatly to the success of a child long long after they’re born, helping to ensure it also survives to reproductive age.

Generally sure. We've certainly evolved to want to be around for a while after reproduction though, for example human infants are completely worthless. That doesn't mean we need to be top notch, but we do need to exist sufficiently to get children to even the most brutal, basic independence.

Compare that to something that hatches then is already just adulting, like many reptiles.

I think the keyword is precocial vs altricial

Both valid points. I will still need some time to take this all into consideration.

No, since you have a nose. Topologically, people have 3 holes.