When did man first create God?
Do you think inception occurred when sapiens first learned how to communicate?
Was it even before this when our animal instincts were influenced by elements of weather, astral bodies, or geological activity?
My thought is that gods were likely first dreamed up with the first story-tellers, and likely changed with the times and the geographic location over generations, but sadly the ones that stuck took hold with the printed word, since once it's set in stone or on paper, it seems to become "truth" and "sacred" where stories are just stories, myths and legends are for entertainment and education about human nature, faults and heroism.
A god is born into the head of each child (or adult) to whom the myth is drilled in as truth, every day. It stays "relevant" only by people talking about it, making laws respecting the "God" and offering holidays celebrating the god of the various religions.
Various cultures had their own creation stories and myths to try to make sense of the world around them. For example, the "gods" and "demi-gods" of the polynesian culture are sacred in that there are stories that are old and ancient, so should be revered as history, but nobody thinks these gods are real in this day and age, nor think they really offer supernatural powers, any more than a totem or charm gives someone courage by reminding a person of their strength. They are seen more as historical myths that helped to shape a culture and helps us make sense of how people thought way back then.
It's definitely time for a new story for this world. Maybe one that unites all the religions into one harmonious multi-cultural all inclusive one world kind of mindset.
James George Frazer in his seminal work The Golden Bough sugests that there is good reason to think priests actually came about before gods.
Priests were the original meteorologist and scientists who noticed the patterns of nature and so could be seen as Rain makers, predictors of the the seasons and weather and knew when the animal prey would come back after hibernation.
Sometimes their would be a freak weather pattern and their predictions would be wrong in such cases they needed a scapegoat and that was an angry god, who was displeased and so was withholding bounty until atonement was made, by organised worship and sacrifice, so long as it was not of the priest.
Just a thought...
Maybe it began when communities started to emerge and socialize, and a fairytale was first used to explain the unexplainable. I can imagine a child asking "why" and having no rational answer then one was made up. I can also imagine that when these stories became popular and spread then someone recognizing an opportunity claimed to have communication with whatever deity in the story of the time and used it to comfort and control the community. Pretty much the same way as witches and demons became an excepted part of society.
Fear of the unknown can create panic and unrest, giving it a name and purpose can go a long way in creating a calm acceptance specifically when there were no facts or evidence to argue against it.
Believing in something was better than the fear created by not knowing.
Probably quite late, in that most early religion was animistic and gave personality to things, but did not conceive of gods as distinct form the things themselves. Gods as such, probably came on to the scene only at about the same time a collective cultures on a large scale appeared. While the idea of a monotheist god did not even exist in, for example, the earliest versions of the Old Testament, much before five or six hundred BCE. If you read the OT you can still find traces of the earlier polytheism, such as references to, our god, as though he was still one of many. Which is also about the same time that the polytheistic Greeks and Romans began to speculate about a philosophical metaphorical mono-god behind the polytheism, as an ideal.
I have often wondered about the massive amount of unpublished material on Koko the gorilla and if religion as a topic was ever broached. Koko did discuss death, very unwillingly, as just darkness. Something like that could give us an idea of our ancestors.