Some people back in the history would answer the question of the origin of monarch with just one word: God.
But from a Biblical (Jewish-Christian) point of wiew I cant find that 100% correct...
In the old testament (first part of the Bible) we can read about the first king of Israel: Saul (Books of Samuel). He became king because the people wanted a king.
God didnt want to give them a king because God didnt think they needed a king, because God was their king and wanted to remain as their king
But the people said: please give us a king, please give us a king, please give us a king, please, please, please...(and so on)
And finally God said: OK,OK ,OK, I will give you a king... And so they got Saul.
From this we can see two things:
1) God did not think it was nessesary with a (another) king
2) the people knew what a king was... They had probably learned it from other people/countrys "in the neigborhood"
For example: At that time they was back from the slavery in Egypth, and in Egypth there was a king (Pharao), so its clear they had a pretty good picture of what a king was...
On the other hand St Paul (I think) is telling that all authority is from God (someting like that) so its not a easy question...
But the historical answer is more about wealth and high culture coming from a rich agriculture. If you have wealth and a rich agriculture some people can afford to not work... and instead spend time ruling...(or fooling around
)
So maybe thats the answer...
I mean for example Egypth is an good example of this... rich soils by the Nile - early culture- early kingdom...
I can compare to my own deep frozen poor country where we got our first king(s) around 800 a.c (Vikings!)...