How I think supernatural creatures gained identities

I think it was through writing, developed in Mesopotamia, that angels and demons, gods and goddesses became something. The animistic and shamanistic spirits were in many belief systems. It was through language that the identities of these spirits developed into tangible individuals. It was also through reading and writing that Persian angels and demons became Judeo-Christian angels and demons. Persian, or Zoroastrian, spirits probably had their roots in shamanistic or animistic cultures.
These cultures may have conceived such spirits, and their influence over man, to explain things and give them more control over their world. A world that was inexplicable without science, and people inexplicable without psychology.
Once, shamans or animists passed on their knowledge of the spirit world. With writing, shamans became prophets. It is indeed amazing that the Old and New Testament hang together as well as they do, being written by so many prophets and priests over so many centuries.