The many similarities we observe among living things is called “homology.” It’s often used as evidence of descent from a common ancestor.

But does similar design mean common ancestor? Well, a car is more similar to a bicycle than to a boat, but this doesn’t mean the car and bicycle are related. They look similar because they were designed for the same purpose and made to function in a similar environment.

And you know it’s the same in the living world. Living things were all made by a common Designer to live in the same world and accomplish the same basic purposes. So it’s no surprise that God used similar designs!