In theory it should be possible for humans to create artificial intelligence since the biological intelligence generated by our brains is simply a product of the behaviour of neurons which either fire signals or remain inactive based on the strength of their input signal.
This type of behaviour has been modelled in neural nets which use Boolean logic - a form of algebra in which all values are reduced to either TRUE or FALSE - to produce a 1 bit binary output (either 1 or 0).
At present, neural nets cannot begin to emulate the incredible complexity and interconnectedness of the human brain, however, and I feel that a much deeper scientific understanding of the brain is required before anything approaching true artificial intelligence can become a reality.