Isaiah 14:12 is a reference to a man and a king...
If you read Ezekiel 28 a few lines before 14, you find that the prophet is addressing a man and a king of Tyre
No contest.
The original language of Job, the word which we read as satan in English was the improper form... Satan in Job is a generic word for adversary...
It looks like someone had problem with God blessing Job and they met "before God" to discuss it.
The reason that the prophets might address kings as though they were addressing something originally from Heaven...
They didn't.
But anyways... we find none of this in depth information in the Bible, so it would be pointless to present it in this forum...
God warned against mixing up with pagans.
Nothing else.
But to further my point it shows that there are angels who are not in God's good graces... angels of false accusation... and when we talk of demons or fallen angels, we are referring to angels that are not on God's good side.
There are many angels that are not on the side of light for whatever reason, the Bible isn't really clear on it.
Can you point to text/s?
Yes, there are many instances of adversaries tempting people and God in the Bible, but it was never originally indicated that each such instance points to the same one...
Never a fallen angel Satan.
As to Jesus' temptation in Matthew, it would stand that He must be tempted as Adam was tempted, so that Jesus could succeed where Adam failed... The adversary in Matthew may or may not be the same adversary that was in the Garden, but I am of the mind that both instances, the events were deliberately set in motion by God.
Jam 1:14-15 explains.