As you can see Beowulf is brave, wise, and benevolent. He faces so many challenges that need all of those abilities. He can deal with others like he can deal with monsters and problems.
In conclusion by definition a hero is willing to do many things. For example he is willing to risk his own life for the good of others, faces danger and does not run away from it, and lastly pursues the danger until it is conquered. Every fight that Beowulf fought showed him doing all three of the characteristics a hero consists of