It's historical fact that the words were written by men.

Some people believe that God told them, word for word, what to write down.

Others believe that the words were inspired by God working in their life and that it's God's message.

These are the two main Biblicalliteralist camps, in a nutshell. The belief comes from a verse about "all Scripture that is inspired," which I believe is in the book of 1st Timothy if I remember correctly. Of course, however, "Scripture" in that day meant something quite different than the 66 Protestant or 73 Catholic "books" of the modern Bible, much less the exclusion of non-Canonical works that were read by some in the early church. And it also doesn't take into account the fact that we literally don't have a single original manuscript of anything that's known as the New Testament today & early transcription methodologies were dubious at best, downright dishonest at worst. If it is "literal" we don't have any way to say that what's read today is the "literal word of God," not to mention the fact that the Gospel of John doesn't refer to the "Word" as something written, rather something that gave voice and meaning to life.

More open Christians instead take the inspired by God to generally mean a collection of written expressions to attempt to put words and voice to the very human exploration of what it means to be human and find an encounter with something divine that defies explanation and gives a meaning to this existence, not as God telling people what to write. Instead it's an invitation into the conversation of what it is to be human, not the why behind our humanity and an explanation of what we must do & believe.