@Alan McDougall,
Well, I do not have enough time right now to properly respond to this, because it would take many pages to make a full response, but I can start on it anyway.
We belong to the same evolutionary family as the Great Apes, but have many distinct features that our evolutionary cousins lack. To say that the smartest chimpanzee is smarter than the least intelligent human is not accurate in any way. Even toddlers display more markers of intelligence than the chimpanzee. It seems that chimps lacks some basic markers of intelligence that the young already possess. That is the capacity to learn. While chimps learn, they do so in different ways that is far similar to imitation than learning. Chimps lack culture that is grown upon through generations, and a chimpanzee can really only learn what other chimps in their group knows.
Chimpanzees have not evolved for millions of years, because they have not been stressed by their environment to change. Humans on they other hand, branched off of the Great Ape evolutionary change millions of years ago, but adapted as their environments have changed. Archaic homo sapiens moved out of Africa, but the chimp never left their native environments so they have never been forced to adapt. Thus, they have no evolved. Given time, and new environments the chimp would likely begin to evolve as well.
Anyway, that is all I am going to say for now. I am taking an advanced biological anthropology course, and human evolution is the main topic that we have studies, which includes a section on all primates, and another specifically on the great apes. It is a very interesting study that I recommend anyone with any interest in human evolution undertaking.