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.
A: Beowulf reveals the essential values of the heroic warrior culture that characterizes Anglo-Saxon and other early Germanic societies. Their values uphold the warrior aristocracy, including loyalty and the high value placed on kinship. As an epic poem, Beowulf embodies the values of its culture. Anglo-Saxon society, as illustrated in the poem, was centered on a warrior chieftain and his retinue of loyal followers who were expected to defend him to the death. Loyalty is essential and is rewarded by the chief's generosity toward his supporters.