@andrew
Yes, both Berossus and Manetho are based on older sources, but the issue is the parallels between the scriptures and the specific accounts of Berossus and Manetho. In addition, while Berossus is based on older sources, what case can be made that Jewish writers would actually have had access to those sources?
Here is the problem that I see. When it comes to the parallels between the Jewish scriptures and other sources, two approaches have been used generally:
1) Just ignore it
2) Propose that the Jewish writers used some ancient source, but don't provide any specifics, just assume that to be the case and move on.
Genesis and the Babylonian material is a perfect example. Yes, there are clearly parallels between Genesis 1-11 and various Babylonian/Sumerian stories, and many people are happy to simply say, "Well the Jewish writes must have known those stories and been influenced by them."
Ok. How exactly? In what way? What about the specific word for word literary parallels? If these stories were only written in cuneiform how is it that Jewish writers were reading them? They knew cuneiform? How is this explained? When and where did they come into contact with these materials? How were the materials transmitted? If the stories originated in the 13th century BCE, and one is proposing that the Jewish scriptures were authored between the 6th and 4th centuries in Persian Palestine, how and why were these stories used? If they existed only on cuneiform tablets held in Babylonian libraries, how did the Jewish writes of the 5thish century get hold of them?
No one has any answers and are mostly happy to simply shrug and move on.
What Gmirkin has proposed, however, is well defined and very plausible. It just has the challenge of moving the writing of the Jewish scriptures up to a much more recent date.
The proposition that the Jewish scriptures were NOT dependent on Berossus, Manetho and other Hellenistic era sources requires a detailed explanation for how it is that there are so many parallels between the Jewish scriptures and various Hellenistic works.
Beyond simply saying that the Jews could have been influenced by earlier versions of the Babylonian works, we have to consider the chances of what happened taking place. Within Genesis we have a fairly concise set of parallels to about 5 or 6 (or more) Babylonian/Sumerian works that have been recompiled in a way to create a new narrative that summarizes and reinterprets these various writings. And our earliest definitive evidence that the Jewish works existed is with the creation of the Greek version of Genesis.
Now, at around the same time, it "just so happens" that a Babylonian priest, Berossus, also "published" a Greek summary and reinterpretation of these ancient Babylon/Sumerian stories, that very closely parallels the Jewish account. So you are telling me this is just a coincidence? Or are you going to argue that Berossus was influenced by the Jews? And again BTW, there is extensive evidence of Babylonian civilization and Babylonian knowledge of these going back over 3,000 years. The earliest actual evidence of the existence of Torah observant Jews doesn't come until the 3rd or 2nd century BCE.
So if you are going to make an argument for independence, then that argument has to be made and be convincing. There has to be some convincing argument as to how it is that these two different Greek writings that summarize and reinterpret disparate ancient Babylonian/Sumerian were produced within decades of one another. If the Jewish Greek writing is a translation of a much older Hebrew work that was produced independently of Berossus and which Berossus had no knowledge of, how is it then that these two writers created so many parallels? How did they both draw upon the same collection of stories, which as far as anyone knows, were never put into a collection together and did not inherently go together?
And this is really just one small piece of the puzzle. That's just Berossus and Genesis, but there are many other parallels as well.
But again, everyone wants to say, "Nah, that can't be", but they don't explain the relationships, they just ignore them or wave their hands.
@SA
What is the "discovery" that Gmirkin is alleged to have made that overturned millennia of Biblical studies?
We can ask the same question about Paul and the Gospels or Marcion or Luke. What we see is that "Biblical studies" is rooted in a lot of flawed assumptions about how documents relate to one another. Specifically, about the order of influence.
For centuries it has been believed that the Gospel writers had no knowledge of Paul's letters. But much of my work, and several other modern scholars, show that this is exactly wrong. In fact the Gospels are based on Paul's letters. The reason there are similarities between the teachings of Jesus in the Gospels and Paul's teachings isn't because both were independently passing on oral traditions that go back to Jesus, but because the Gospel writers were using Paul's letters as the source for teachings to attribute to Jesus.
So, no, there is no "new discovery", there is just a fresh interpretation of the same old evidence. This applies to both Old and New Testament studies.