What is the central issue of Beowulf?

I tend to believe there are several central issues, among them heroism, absolutely.  However, there are also other issues present. One of them is self-sacrifice and its cost.    Beowulf chose the life of a hero, which meant he would have to live a life of constant danger and with the knowledge that he could be killed at any time when he chose to defend others, etc. He chose to sacrifice many normalcies of life in order to be a hero.  Being a hero came with man costs.  In the end, he sacrifices himself (even when he is old) to defend his kingdom and loses his life in the process.