In purely Darwinian terms the state of change and mutation is not a gradual upward slide but more like a series of successful, near-seeming coincidental events that shape a general trend towards more complex states of organism. In random terms just about anything could happen, while intelligent design is the deliberate shaping of probabilities along a fixed determine line. The point of it all is...environment has as much to do with the outcome as any deliberate intention.
The actual theory proposed by Darwin and Mendal would have it that the goal of reproduction is the perpetuation of the species...but only a form that is viable to existing environmental conditions tends to live to an age where it can reproduce. The human form has proven very resilient and adaptable over the centuries. Yet the variations of different competing environmental systems have resulted in a wide range of different characteristics, not all of them comparable to the form of the Neflim template known as Adam.