It is both one book with one author and one story and yet a collection of writings, from multiple authors, from different places, using different genres yet consistently agreeing with one another. It is both one book and many. It both has one author and many. It is both of these things that speak to its consistency and act as strong evidence it is, indeed, divine revelation.
One of the interesting things about the Bible is that it is both a single book and a collection of books. It has both a single author and multiple authors. It is both one story and yet multiple genres, stories and writings.
At any given moment, there is usually a push to treat it more clearly as one or the other. So, lots of people have made effort to ensure that we preach the Bible as one story – which it is – but then can so emphasise the oneness of the story and overarching author that it flattens the differences between the multiple authors. Others, by contrast, so emphasise the different authors and genres that they almost (or, sometimes, totally) ignore the fact that there is one storyline to about which the whole thing points in every part.
There are often different occasions to emphasise one thing or another. So, in preaching, I tend to emphasise the oneness of the story for believers reading the scriptures in light of the Christ to whom they point. Whether reading Old or New Testament narrative, poetry, prophecy or history the emphasis falls hard on the primary author (God) and the key to the storyline (Jesus Christ) and the reason for his coming and the occasion of any promises (the gospel). Whilst we are, of course, looking at the details of this particular book, we are concerned about them so far as the overarching storyline goes too.