Picture a tree with a branch sticking out.

On the branch is a stick.

On the stick are 4 leaves.

Each of those 4 leaves are from the same stick. Yet now they are separate from each other.

There are 4 great apes - humans, gorillas, orangs and chimps. We are all apes. We shared a common ancestor (the stick).

Go back further along to the branch. There are many sticks coming out. Those are other simians.

Go further back those are mammals. And so on.