As we do this we come across the point of who Christ claimed to be. As C.S. Lewis put it,
"You must make your choice. Either this man was, and is the Son of God: or else a madman or something worse...Let us not come with any patronizing nonsense about His being a great human teacher. He has not left that open to us. He did not intend to." So as one justly and diligently reads the Scriptures you cannot deny the fact that Christ claimed to be God. So given that point one must then ask the question posed in the title, Would man really write the Bible if he could?
As Lewis S. Chafer, founder and former president of Dallas Theological Seminary wrote, "It (the Bible) is not such a book as man would write if he could, or could if he would."  In other words,
"Man would not write the Bible, for in doing so he has created a message of the perfect Son of God who condemns all men. Since God will judge sin, no rational man would write a book that would be self-condemning." 
Furthermore man could not write the Bible if he would because of the simple limitations on human understanding. It would be most impossible for an imperfect creature like man with limited rational capabilities to conceive of an unlimited God who is certainly most-powerful with his accompanying eternal attributes.
So to answer the question, above, I would say no, man would not write the Bible if he could for the reasons above. That point given, then the author of the Scriptures had to be God himself. As Scripture attests, "All scripture is God-breathed..." (2 Tim. 3:16)
1. C.S. Lewis, Mere Christianity (New York: MacMillian Company, 1952), 40-41.
2. Lewis Sperry Chafer, Systematic Theology (Dallas: Dallas Seminary Press, 1957), 22.
3. Elmer L. Towns, Theology for Today (Mason: Cengage Learning, 2008), 46.