Intelligence – as much as is needed and no more – is widely found throughout God's creation. So intelligence alone is not what makes man special.
Consider the weaverbird. The nest of the weaverbird is woven of strips of fiber and grass. Using beak and feet, the male uses loops and knots to weave its hanging nest. Then, the nest is inspected by a prospective mate. If she doesn't like the nest's construction, she turns down the hopeful male. The male then rebuilds the entire nest. Some males have been seen re-building their nest two dozen times before being accepted by a prospective mate. Certain weaverbirds actually build cities of nests protected by a woven roof. One roof was 15 feet across! Now, all this requires a certain level of intelligence.
So it is not intelligence that sets man apart from the animal kingdom. No, it is the fact that our Creator made us to have a special relationship with Him. Even though we are a pretty bad lot, God loved mankind so much that He chose to die as Jesus on the cross that we may be forgiven. Anyone who has accepted Christ in faith has the promise of being made a new creation, beginning right here in this life and into eternal life in the next! That's the wide gulf between man and animal!