That's quite the claim, since historical evidence sure seems to show every known biblical text was scribed by human hands.
> yet it's unified in the story
That's certainly open to interpretation, to say the least. Many of the story elements and arcs can be found in cultures that pre-date Christ.
> much of which was has already come to pass about nations or events
Over thousands of years one can find examples for any broad prophecy.
Once again we're left with nothing authoritative on the matter except the word of Man, that we're apparently expected to take on faith alone.