It just seems to me that this is a discussion that can only boil down to faith. Personally as a Christian I think it is a mistake to put too much faith and emphasis on the Bible. Even the Bible itself says that Jesus is the "Word" of God.
Genesis tells us that God created and if you like even talks about some form of an evolutionary process. Whether that all came from other mythologies or not in my view isn't germane.
I've posted this before, but I like what CS Lewis writes about this.
quote:
Just as, on the factual side, a long preparation culminates in God’s becoming incarnate as Man, so, on the documentary side, the truth first appears in mythical form and then by a long process of condensing or focusing finally becomes incarnate as History. This involves the belief that Myth is ... a real though unfocused gleam of divine truth falling on human imagination. The Hebrews, like other peoples, had mythology: but as they were the chosen people so their mythology was the chosen mythology - the mythology chosen by God to be the vehicle of the earliest sacred truths, the first step in that process which ends in the New Testament where truth has become completely historical.
Miracles Ch 15 CS Lewis
Everybody is entitled to my opinion.