Why do you know more about king at sutton hoo than saxon?

Sutton Hoo is a location where centuries of burials took place along with Saxon tribes buried a ship and other burial goods. What is known is what has been found and researched by historians. There wasn't a "king" at Sutton Hoo, in fact, historians are not sure who exactly is buried there. Your question is basically asking the same thing about the same people.