mouse quoted The Sumerians by Samuel Noah Kramer
The Sumerians, the pragmatic and gifted people who preceded the Semites in the land first …
...the king, or as he is known in Sumerian, the "big man"...
— The Sumerians by Samuel Noah Kramer (Page 74)
Props to the children's pamphlet I just read that went into detail about the etymology of "lu(2)-gal" as lu(2), meaning man, and gal, meaning big, which form a compound word in Sumerian, an agglutinative language, as well as providing the cuneiform characters.