This is a scholarly debate with no consensus. As scholarly debates go this one is rather technical. Yet in 5 minutes (well actually 6) I’ll try to give you the core essential issue, and also suggest how awareness of this can help us read the Bible better.
Please let me know whether I succeeded!
Hi Tim, from the ancient texts themselves – at least since the incorporation of the te’amim into the text – probably quite early (See David Mitchell in Jewish and Christian Approaches to the Psalms) – we have two distinct systems of signs, one for the books of truth, Psalms, Proverbs, and the speeches of Job, and another for the rest of the Bible.
It is convenient to call this distinction – and I agree that there are both large and small snippets of similar styles in most books – prose and poetry. (I see that 2 Samuel 22 uses the ‘prose’ signs where Psalm 18 uses the ‘poetic’ – how curious!)
Yes, that difference in “pointing” (this and the Hebrew te’amim are ways of talking about the signs added quite early around the consonants to indicate how to pronounce and chant) are evidence that those books (or in the case of Job, as you noted not the prose story that frames the book) were viewed as “different”. But again as you note the poetic system is not used for poetry elsewhere in Scripture. So evidence for a dichotomy quite early (some time between the Dead Sea Scrolls and the 10thC AD). But not conclusive evidence. Typical of the other arguments too 😉