Urmonotheismus (German for "primeval monotheism") or primitive monotheism is the hypothesis of a monotheistic Urreligion, from which non-monotheistic religions degenerated and is supported by a number of scholars. Judeo-Christian scripture supports this view.
Evolutionary biologists argue for Judeo-Christian scriptures as mythology so dismiss them out-of-hand. They argue preanimism, then animism, totemism, polytheism and finally monotheism developed based on the archeolological evidence; however, the physical evidence does not "prove" that the first modern humans were not monotheists... it's just their best guess after dismissing ancient manuscripts that assert it as myth.