Answer :

The social classes of Sumer were organized as how ppl in those times considered the importance of each group of ppl with different jobs. This is the social status of Sumer from highest to lowest:
-Kings-
-Priests and scribes-
-Traders, Craftspeople, Merchants-
-Slaves-

If u have any more questions, feel free to ask me! Im studying Sumerian Civilizations
The social classes were divided in 3. Top: King, Government Officials, Soidiers, Priests(maybe scribes)
Middle, Farmers, Merchants, Fishers, Artisans.
Lower: Enslaved people, Criminals, Unskilled worked.
Hope this helps (and don't say I only want to get points because I've been learning this and  knew this question was coming up)