And where would that "intelligent principle" [aka a deity] come from? If life on Earth is somebody's experiment in a cosmic Petri dish, the problem would merely become the natural genesis of experimenters. Reductio ad infinitum. Hierarchically working natural selection does answer the mail, at least for the purposes of work in my field [I happen to be a chemist employed in genetic engineering].
Many don't see that the word "intelligence" is very broad.
An organizing principle can be an "intelligence."
In fact, many computers do complex organizing, but none of them are living.
"Natural Selection" was an organizing principle that was applied to all of life as we know it. It has failed as an explanatory organizing principle. The world around us is too complex for natural selection to adequately explain.
The "intelligent design" criticism of evolution says that another organizing principle must be found.