In the predominance of Jewish literature, this poem (Is 14) is interpreted as referring to the death of an Assyrian king, probably Sargon II who was slain in battle 705 BC, and was layer reinterpreted as predicting the death of a Babylonian king.
Verse 9 makes reference to Sheol and his arrival there. Verse 11 of my “Jewish Study Bible” reads,
“Worms are to be your bed,
Maggots your blanket.”
and are close enough to the King James Version to suggest an amalgam of Sheol as a garbage dump outside of Jerusalem is being suggested. There are several other such verses which tend to reinforce this view.
“O Shining One, Son of the dawn...” is also seen in rabbinic literature as the planet Venus, and is thought related to Isaiah’s knowlege of Greek and Cannanite mythology where an insolent young king is thrown down to earth by a higher deity.
The Book Of Job exibits at least four compostional styles, and likely as many different authors from the mid 6th to 4th centuries BC. It is also generally considered in the Talmud to be a work of fiction.
And again, it is the human mind and nothing else that this Devil affects. While God appears to have been quite active in the universe before the appearance of mankind, where is this thing elsewhere?
Certainly the biggest portion of [human/demon] interaction is with the mind (i.e. Jesus casting demons from the madman), but this does not mean that it is exclusive thereunto. The interaction between Satan and Jesus has Satan offering all the world to Jesus: Jesus did not engage him on the level of having the authority to do so, but rather on the level of what God's law said... if the devil were only a thing of his mind, and if Jesus is God, then there would be no wrong in worshiping Satan as he [Satan] would be God. Therefore Satan must be a different 'thing' than God.
While God appears to have been quite active in the universe before the appearance of mankind, where is this thing elsewhere?
I'm not sure, I wasn't there... nor is my gift of insight that sharp.