Ancient cheetahs in fact were very slower only running a top speed of 20 mph. That happens to be 40 mph less than present day cheetahs
The cheetah has competition for food in their area. Their is also a widespread of animals in the Savanah where they live.
Cheetah's adaptations have drastically changed over the years through natural selection needing to get food and reproduce
Cheetahs weren't always as fast as they are now. This speed that they have now was acquired during natural selection. This speed allows them to hunt food better, ultimately having better reproduction efficiency.
Natural selection has changed the way we look at cheetahs. If cheetahs didn't get these adaptations they might even of been extinct a long time ago. Natural selection has helped cheetahs become survivors.
Cheetahs have bodies built for speed. They have long legs which give them longer strides. They have an elongated spine for additional flexibility and back movement. Cheetahs also have very well adapted claws to grip the ground for excellent traction.