To quote Brian " how do we know that these tales predate the bible events?" when he ask this question he is on a different subject. he is now on the subject of etymology, modern day languages are limited to Semitic languages, and not the language of the Sumerian's, in fact the Akkadian's had their language and the Akkadian's also had the Semitic languages. A thing about the Semitic language is that it includes 77 sub languages, such as Greek, Hebrew, Aramaic, and others but does not include Sumerian language.
Even Biblical Scholars would agree that the first author of the Bible was Moses, who authored the Pentateuch or the 1st five books of the Bible .
So when you ask that question you assume what many Christians assume that "Adam & Eve" the story of them in the Bible was penned as it was happening this is simply not true, that story existed well before Moses was around (and I will not get into or discuss the existence of the Moses character in the Bible, so let's assume there was a Moses for the moment).
To note Christianity is a religion and not a society, because a society encompasses a religion, a way of life, laws, holidays, and so on and so forth and not the other way around.
"Moses" may have been the first author of the Bible, but "Moses" didn't exist at the time of the Sumerian's, as they predated "Moses". In fact in Genesis 2 we find that the Bible indirectly talks about the cradle of civilization when the Bible references the Euphrates river, which is inherently next to the Tigris river. The oldest etymologies of languages are the Sumerian, and no one denies this, in fact a Biblical scholar named Dr Kent Hovind has admitted that there were tribes and people before "Moses", that is powerful coming for a Christian Scholar.
So please Brian keep in mind that a majority of these ancient stories have everything to do with etymology.