//If man arose without intelligent guidance, why should he have intelligence? Can unintelligence create intelligence? //
Yes. DNA is prone to mutations. Mutations lead to variety. Varieties compete on all levels (physical strength, mental agility etc.) and any competitive edge will enhance reproductive success. One recurrent theme, in the animal kingdom, is that larger brains became the factor which best enhanced survival and breeding success.
At some stage, a capacity for abstract thought arose. It's difficult to work out where on the evolutionary tree this might have been but chimpanzees, which have been taught sign language, appear capable of stringing together short sentences of their own devising - not merely mimicry of things their trainers taught them. One was even able to form its own compound words, to request a fruit for which it had not been taught the sign for.
Abstract thought from a pink gelatinous blob made from proteins, cell membranes, water and minerals.
Not bad eh?