The book of Job is the script for an ancient Greek style play
The book of Job perfectly matches the style of ancient Greek plays at the time. You have the starting prose in which gods bicker among themselves and one issues a challenge to the other. You have that challenge impacting the life of a mortal man. The middle is filled with philosophical arguments given by the main cast, and finally God himself comes down in a dues ex machina to deliver the final argument and restore the mortal. It's beat by beat in the style of an ancient Greek play.
Some possible counters:
1. The book of Job takes place near the time of Abraham
It's a play, it can take place at any time
2. Copies of Job where found in the dead sea scrolls
The dead sea scrolls were dated to 1-3 century BCE, Greek plays had been going on since 6th century BCE so plenty of time for it to be written
3. Ezekiel mentions Job
Ezekiel was from around 6 BCE, so about the time the Greek plays were starting, but it's iffy if it could be written in time for Ezekiel to write about it. He also mentions Noah and Daniel, and yet Daniel was at earliest a contemporary, and more likely written after the time of Ezekiel.
It's likely that Ezekiel was not meaning Daniel from the book of Daniel, but rather a character named Dan’el from the epic of Aqhat due to the spelling in Hebrew. He was a legendary figure that Ezekiel would have been aware of, and would put him in the same category as Job and Noah. What this means is that Ezekiel had no problem bringing up a legendary figure from a story, so the same could be said of Job. If Job was a legendary figure of Jewish tradition, then Ezekiel would have known of him, and that legend could serve as the basis for the book of Job.