People write for different reasons? Maybe. But it boils down to one thing; they have a passion or at least a strong desire to write for whatever reason. Now, it may be true that passion or desire comes about for different reasons, but the "want" is the only thing which drives one to write. One simply doesn't write if they don't have that passion from where ever it comes. Otherwise, they will not put words to paper unless "forced" to do so by some outside agent such as a teacher or other authority figure or perhaps an attempt to keep from starving so to speak.
Yes, lots of good stories in the Bible and they pretty much all were written because of the passion to write those stories. They most certainly weren't written by God, either personally or dictated. They were written by men who had a passion to preserve their accounts of what they believed. They
wanted others to accept their version of the story and often the different authors presented different versions of basically the same story because their passion had different details which they wanted to espouse.
So, I would say, yes, we may write for different reasons in a sense, but those different reasons are because of different passions or degrees of desire. Just an opinion of course. Take care. Vern