YECism “word of God?” Interstesting that you follow that claim with something no where to be found in the Bible, namely “Noah and Shem, and handed down in the form of cunieform tablets.”
There are a number of things that are not directly stated in the Bible that we hold to be true. The authorship issue is derived from the use of the word toledoth 11 times in the Book of Genesis. It is not settled doctrine, but there are strong implications that it is true.