Is god a figment of the collective human imagination? ?

The concept of a "God" falls under the same category as the concept of "superman". Humans can imagine other beings. They attribute qualities to these beings to better survive encounters with those beings. Those qualities can be out sized. In the concept of superman and God these qualities are taken to the infinite. In the most basic sense, yes, a god and a superman is a figment of the human ability to imagine other beings.