The Old Testament is a complex and diverse book. How does the compilation and composition (kinds of literature) show this complexity and diversity?"
First of all, we need to understand that the "Old Testament" is really called the "Holy Scriptures" or else simply the "Tanakh." This last word is a shortened form of three words, Torah, Nevi'im, and Ketuvim. These are the three divisions of the Scriptures. Torah refers to the first five books of Moses (the Pentateuch), Nevi'im means "Prophets," and Ketuvim means "Writings." Therefore, we immediately see an outline of how the Scriptures are divided into three main categories which teach us something about the diversity in the Tanakh.
To learn more, we need to look into what books each of these three divisions include. We'll start with the Torah.
The Torah is made up of five books: Genesis, Exodus, Leviticus, Numbers, and Deuteronomy. Typically, they are considered to have been written by Moses under direct inspiration from G-d. However, if you look at the internal evidence within Genesis you will see that it was written by numerous authors who lived at the same time as the events they describe. These separate sections are noted by the repeated phrase "these are the generations" which is found through Genesis. Therefore, although it is true that Moses put Genesis together, he put it together by compiling numerous written records that were already in existence and available to him. This leads us to another interesting question. Who ...