why and how was okonkwo one of the greatest men of umofia

I just included a quote from Chapter 1 that pretty much explains it.

Okonkwo was well known throughout the nine villages and even beyond. His fame rested on solid personal achievements. As a young man of eighteen he had brought honor to his village by throwing Amalinze the Cat. Amalinze was the great wrestler who for seven years was unbeaten, from Umuofia to Mbaino. (1.1)

Okonkwo gains respect for himself and his village by proving his mettle in a physical contest – wrestling.