A constitution is a statement of the basic principles and laws of a nation, state, or group, such as the U.S. Constitution. Another very common meaning of constitution is the physical makeup of a person. So think of a constitution as how a body (yours, the government's) is set up. If you have a strong constitution, it means you don't get sick very often.
I think the focus of the story is on Beowulf as a hero rather than a king because it is his heroic deeds that lead to him being offered the throne. Also to be king one must possess some type of heroic qualities in order to rule a land and its people.
Itâs obvious that heroes are defined by their actions, as Beowulf is characterized by his strength and courage throughout much of the epic. The focus of the story on Beowulf as a hero rather than as a king serves the purpose of showing the value and expectations that the Nordic culture puts on its leadership.