I will stretch another category a little. I will pick for
Inventor,
Sennacherib of Assyria.
My reason being that I find ancient history fascinating especially the time period when humans moved from hunter gatherers to farmers. As soon as this draft was announced I wanted to pick as a scientist or innovator or whatever category someone ancient from Mesopotamia, the Indus valley, Egypt, or China that made a distinct advancement in agriculture, specifically irrigation.
Sennacherib while also a king, was a very scientific technical person. Of course he also laid waste to the greatest city of the time, Babylon; but did rebuild it later.
While no one person can be credited with a specific advance in agriculture as inventions and improvements were made at the same relative time in the above four areas of the world, I choose Sennacherub for his efforts.
The importance of agriculture is highlited by the fact that mankind since creating tools has spent only 1% of time building a civilization, the rest merely surviving. The advances in farming allow an area of land to support 20 to 200 times the people, and allows for some people to move from hunting/gathering to specialized occupations.
Back to Sennacherib.In Nineveh he created public and private parks watered by irrigation. Ten miles north he dammed a river and had the water arrive in the city at a higher grade than the Tigris. That allowed the people to gather water/irrigate without hoisting.
He built canals, a canebreak, imported cotton trees and a 12 mile irrigation tunnel. His greatest feat, in an effort to bring even more water to Nineveh, was a thirty mile irrigation canal which included an aqueduct. Amazing for the time.