Who wrote the book of Genesis?

Who wrote the book of Genesis, and how did they know the facts?

These are simple excerpts of sources that I studied in preparation for the October 2, Deacon and the Rev. video. I use Bible Hub (a free app and online service filled with bible translations and study resources. One excerpt was taken from my Kindle version of The New Living Translation Study Bible.

Oral tradition source of facts.

Clarke's Commentary, Preface to the Book of Genesis.

"Thus it was easy for Moses to be satisfied of the truth of all he relates in the book of Genesis, as the accounts came to him through the medium of very few persons. From Adam to Noah there was but one man necessary to the correct transmission of the history of this period of 1656 years. Now this history was, without doubt, perfectly known to Methuselah, who lived to see them both. In like manner Shem connected Noah and Abraham, having lived to converse with both: as Isaac did with Abraham and Joseph, from whom these things might be easily conveyed to Moses by Amram, who was a contemporary with Joseph. Supposing, then, all the curious facts recorded in the book of Genesis had no other authority than the tradition already referred to, they would stand upon a foundation of credibility superior to any that the most reputable of the ancient Greek and Latin historians can boast. Yet to preclude all possibility of mistake, the unerring spirit of God directed Moses in the selection of his facts and the ascertaining of his dates. Indeed, the narrative is so simple, so much like truth, so consistent everywhere with itself, so correct in its dates, so impartial in its biography, so accurate in its philosophical details, so pure in its morality, and so benevolent in its design, as amply to demonstrate that it never could have had an earthly origin.. In this case, also, Moses constructed every thing according to the pattern which God showed him in the mount".

Documentary Hypothesis source of facts.

New Living Translation Study Bible, Introduction to the Pentateuch page 71.

"Critical scholars since the mid-1800s have argued that the Pentateuch was written no earlier than the 600s BC and is the product of a complex literary evolution. The prevailing critical view, the Documentary Hypothesis, is that Genesis - Deuteronomy were compiled from various sources by different groups of people. This hypothesis uses the different names for God, repeated stories, and theological emphasis to propose that the Pentateuch comes from four sources; J ("Jahwist"), E ("Elohist"), D ("Deuteronomic"), and P ("Priestly"). It is thought that these sources were written and collected between 850 BC and 445 BC, gradually being combined and edited until around Ezra's time (400s BC). This theory has prevailed in the scholarly world since Julius Wellhausen made it popular. However, advances in literary studies are again pointing back to Moses as the primary author of the Pentateuch".

Written records source of facts.

Ellicott's Commentary for English Readers, Preface section II The Literature of the Patriarchal Age.

"Whether there were any written records in the earliest age of that people, in the period commonly known as the patriarchal, is a question on which we cannot speak with certainty. W have no Hebrew inscriptions of that period, and the Moabite Stone, with its records of the reign of Mesha, a contemporary of Ahab, is, perhaps, the earliest record in any cognate alphabet. Egypt, however, had, at the time, its hieroglyphics and Assyria its cuneiform characters. Coming as Abraham did from Ur of the Chaldees, and sojourning in Egypt, as the honoured chieftain of a tribe, he may well have appropriated some elements of the culture with which he came in contact. Now, first, modern discoveries have shown that there is no difficulty, as some have supposed, in believing that the patriarchs could read and write. Ur of the Chaldees, whence Terah emigrated proves to have been a famous seat of learning, and Mr. Sayce (Chaldean Genesis, p.24) says that the earliest inscriptions of any importance which we now possess belong to the time of a king of Ur, supposed to have lived three thousand years before the Christian era.

These inscriptions, he adds, consist of texts on bricks and on signet cylinders, and some of these latter may be, he thinks, of even grater antiquity. Even the daily transactions of business were in Abram's time perpetuated with the utmost punctuality and decorum by means of those contract, and sale, and even loan tablets of terra cotta which are still existing; and it is now known that in Chaldea among the Accadians, as in Egypt, papyrus was used as a writing material as well as clay, and more rarely, stone (Tomkins, Studies on the Times of Abraham, p. 45). So far from losing, the Book of Genesis gains infinitely in value and importance, if not on its divine, yet on its human side, if we find reason for believing that we may have in it the contents of bricks and cylinders carried by Abraham from Ur to Haran first, and thence to Canaan".