Exactly, and yet they can not even yet produce a single living cell from scratch.
But if even if they could come up with a better design, it would not be proof that we were not intelligently designed. We know that we were created lower than the angels. We know that we were subsequently cursed with mortality, illness and disease as a result of the fall. We don't have the eyesight of an eagle, the speed of a cougar, the strength of a lion, and yet we dominate the earth as instructed to by our Designer. We are designed the way He wanted us, nothing more and nothing less.
They expect us to believe that something happened by accident that they can't even do on purpose, and then when they can do it on purpose, continue to insist that intelligent design is not how life came into existence but it arose by itself, when they still never demonstrated that it could on its own.