When humans design things, we use top-down, bottom-up, and iterate design:
Top-down design: I want to make something that drives. I'll need wheels, somewhere to sit, a way to steer, etc. *Makes car*
Bottom-up design: I have a car. I think it would be better with/without a horn. *Adds/removes horn*
Iterative design: I invented a touch screen. I'm going to put it on the car radio. And this phone. And this tv. And this oven. And this GPS. Let's just go ahead and roll it out to all electronics.
Evolution is a bottom-up mechanism. Every organism must either mutate its own traits or inherit it from an ancestor. If sharks develop cartilage that is resistant to cancer, it does not get rolled out to humans. Animal eyes do not get rolled out to squids; they have to develop their own independently. Creatures do not spring into existence out of nowhere; they must come from a prior species.
So, if this was a world of creation, we would expect to see evidence of top-down design, bottom-up design, and iterative design. If this was a world produced by evolution, we would only expect to see evidence of bottom-up development.
We only have evidence of bottom-up development.