Here is a chart designed to help you understand (1) the relationship between novels and other written works, (2) the characteristics that tend to make up various kinds of written work, and (3) the general historical trend in fiction writing. As with all neat and tidy schemes, of course, this one oversimplifies and must submit to many exceptions. But it might serve as a quick orienting schematic for the original grasp of understanding.
From the beginning of the novel (whether that means to you second-century Greek romances or eighteenth century picaresque works) to today, the historical trend has generally been from right to left for the characteristics listed above. What may look like a movement from the complex to the simpler could be attributed to the democratization of reading: more and more readers with less interest in, say, allegory or philosophy, are buying novels. And a case could also be made that simplicity of presentation is nevertheless conveying complexity of thought and symbol. What other historical or societal changes might explain this movement? The rise of individualism? The emphasis on feelings over thought? Other events or trends?
Both the top row and the scales above are continua. Thus, for example, history that generalizes is closer to fiction than to journalism. The novel (at least in the eighteenth and nineteenth centuries) tends to be a work that blends elements from both ends of the continua (particulars and universals, character and action, and so on).
An instructive and entertaining exercise is to consider the books you are reading and locate them at appropriate places along each of the scales (you can even connect the dots into lines, if you wish, thus creating a graph). Before you begin that, however, you might use a few well-known works as “reference” works. Where, for example, would you put Shakespeare’s plays on each continuum? Where would the Faerie Queene or Wuthering Heights go? What about a modern thriller you have read?
As with any tool, after you have completed this exercise, ask yourself, “So what?” Does this help you understand the work, the context of the work, or the movement of literature in history? Are there “throwbacks” or “visionary” works among those you have graphed? Are the patterns similar or widely different? Why? So what?