Early on in our study of Genesis, it is valuable to know who “wrote” Genesis One. Generally, it is accepted that Moses wrote Genesis, along with Exodus, Numbers, Leviticus, and Deuteronomy.
However, I put the word “wrote” in quotes because it doesn’t completely apply. Moses may have written the words of Genesis on scrolls, but he couldn’t author it, because it predates him by twenty-five centuries.
So, either it was handed down from previous generations, or else it had to have been dictated to Moses by God. In either case, he didn’t author Genesis. So, Moses can be considered an editor of sorts.
So then, who did write it? Well, in the case of the first five creation days, only God could know that information. So, either he dictated it to someone, or wrote it Himself.
We looked over the multiple styles in Genesis when we talked about toledots, the markers at the start of sections. There are eleven, and Genesis one doesn’t have one. So, that makes (probably) twelve authors. It’s possible that there were less or more, but that’s a good guess.
Then Moses transcribed or edited those texts, and put them together into the Genesis that the Israelites used.