How Genesis was Written

Good morning!
I apologize for my rather "lengthy" (by my usual custom) absence.  Had I known in advance the events of the past several days, I would have postponed my first Genesis post.  This second in the line-up has been delayed by a combination of personal illness as well as death in my sister-in-law's immediate family, in addition to some unyielding deadlines related to volunteer work.

Today, we are going to explore in more depth how Moses wrote the book of Genesis.  There are a few theories as to how this occurred, although none of them can be definitively proven as "the one".  I present them to you for your consideration and will then tell you the one to which I subscribe.

1.  Oral Tradition
This theory declares that the material in the first five books of the Bible (The Pentateuch) was passed down from father to son, priest to priest, orally ... only.  It puts forth that Moses was the first of God's men to generate an written record.

2.  Direct Revelation (only)
It is pretty clear from scripture that God wrote with His finger the 10 Commandments on the tablets of stone, and that afterwards Moses descended from the mountain (Sinai) with them, to present them to the people of Israel.  We find this miracle recorded in Exodus 31:18 (ESV).

And he gave to Moses, when he had finished speaking with him on Mount Sinai, the two tablets of the testimony, tablets of stone, written with the finger of God.

In Exodus 24:12 and Deuteronomy 9:10, it seems that more than just "the 10" were given in this very direct, divine manner.  But...how much more?

12The LORD said to Moses, “Come up to me on the mountain and wait there, that I may give you the tablets of stone, with the law and the commandment, which I have written for their instruction.”

Exodus 24:12 (ESV)

(This took place just before Moses ascended to the peak of Mt. Sinai, where he remained for 40 days and 40 nights.)

And the LORD gave me the two tablets of stone written with the finger of God, and on them were all the words that the LORD had spoken with you on the mountain out of the midst of the fire on the day of the assembly.

Deuteronomy 9:10 (ESV)

(This was Moses' testimony, after the fact, after his 40 days/nights on the mountain.)

What about the rest of the Pentateuch?  Was it, as some claim, given to Moses by direct divine revelation, while he was on Sinai or during the time he lived/worked in Midian (before the Burning Bush incident), or why the Israelites wandered for 40 years in the desert?  Moses WAS on Sinai for 40 days and 40 nights, you know.  In all that time, could it be that God gave him by direct revelation ONLY the information in Exodus 24-31?

3.  Combo
This theory to explain Moses' writing of the Pentateuch is that he received some of it by direct revelation (see above), and that to codify the rest he was led by the Spirit of God to use other primary source materials from eye-witnesses (divinely-inspired texts unknown to us today yet) available to him in that day, over a period of time.  By this theory, he compiled the writings of other men of God, along with the direct revelation God gave to him.  As the apostle Peter testified (1 Peter 1:16-21 ESV)

16For we did not follow cleverly devised myths when we made known to you the power and coming of our Lord Jesus Christ, but we were eyewitnesses of his majesty. 17For when he received honor and glory from God the Father, and the voice was borne to him by the Majestic Glory, “This is my beloved Son,ⁱ with whom I am well pleased,” 18we ourselves heard this very voice borne from heaven, for we were with him on the holy mountain. 19And we have the prophetic word more fully confirmed, to which you will do well to pay attention as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts, 20knowing this first of all, that no prophecy of Scripture comes from someone’s own interpretation. 21For no prophecy was ever produced by the will of man, but men spoke from God as they were carried along by the Holy Spirit.

4.  Pious Men (JEDP Theory)
This theory purports Moses did not write the Pentateuch at all, but that it was compiled by a variety of nameless "pious men" who cobbled it together from Babylonian and Canaanite myths, from oral tradition, etc.  Those who subscribe to this explanation deduce, therefore, that the Pentateuch is a "pious fraud", as opposed to divinely-inspired Word of God.

The picture at the top of today's post is from the aforementioned voluneer work I'm currently helping with.  To achieve the desired outcome, I have taken 5 different texts on the same theme, and have cut them apart to group them according to their similarities/differences.  This work may be divinely appointed, but it is in no way divinely inspired, lol! 

So, how did Moses write the Pentateuch?
First of all, I agree that Moses IS the instrument God used to communicate His Holy Word to us in the first five books of the Bible.
Of the four theories above, I reject #s 1 and 4.  As for #1, it is implausible to believe that there were no written records from the earlier patriarchs, those prior to Moses.  (For instance, Genesis 26:5, which makes it clear Abraham had written laws of Jehovah, laws which he kept.) .
As for #4, that theory is downright heretical, as it emasculates the entire Penteteuch by rendering it nothing more than a collection of disparate myths.

After examining these various perspectives, I believe #3 is the most likely, keeping in mind that God Himself, through His Spirit as described by the apostle Peter, was in total control of His own written revelation to man.  But, I'm not going to be dogmatic about my viewpoint here.  It could have just as easily been done through #1, as described above.

Additional notes:  the Pentateuch is one continuous book.  The first word of the book of Exodus, for instance is often translated "Now" or "And", which naturally establishes the book as a continuation of Genesis.  The five divisions into "books" was done as a matter of organizational convenience. 
Most likely, as with earlier source materials, the Pentateuch was written on clay tablets.

Sources:

http://www.biblearchaeology.org/post/2005/12/26/From-What-Did-Moses-Compose-Genesis.aspx#Article

https://www.gotquestions.org/toledot.html