why do scholars believe it is 2 stories woven into one?
Because there are clear indications that there are two stories.
One story had Noah bring 2 of each animal; the other has him bringing 7 pairs of "clean" animals.
One story has the flood lasting 40 days of rain and then three weeks while the other has the flood lasting a year.
In one story, God opens the ark; in the other Noah does.
I separated the two stories for you.
when did scholars first decide that various scribes started interweaving their own stories with older stories?
I don't think they did.
The two stories represent two ancient traditions of the experience of God.
There no suggestion that scribes started weaving their own stories.
i have heard many scholars and theologians say the bible is a collection of man's writing about his experiences with God - is that true?
I wold say, "No."
Every writer did have a personal experience with God just as every indivual's experience of everything is he own personal experience.
But the Bible is not about individuals' personal experiences. It is about God's self-revelation to man.
My experience comes from me.
God's revelation comes from Him.
or is the bible God inspiring various men to receive and write down His words? -
That depends on what you mean by "His words." If you mean that God dictates the exact words that the writer is to use then I doubt it.
God inspires men to write. I think men write using their own vocabularies and their own writing skills. It's not the exact words that are the key to the communication. The key is God's message.
And, remember, we are reading writings from ancient, near eastern literature that is imbued with the culture of their time and place, which have been translated into the language of a modern, western, scientific/industrial/technical/information-age culture. So, even if God dictated the exact words that the writer was to write, when they were translated into modern English, something is lost in translation from ancient Hebrew and Greek to Modern English.
But God, who told the disciples to preach the Gospel to the whole world, knew that would happen. So what He communicated was His message, not the words.
Am I making any sense?