Beowulf, as an epic poem, has endured—passed down by word-of-mouth through generations long before it was recorded on paper— because of its tone of selfless heroism and honor. The sense of greatness present when we read Beowulf today comes directly from the hero first in how he handles himself, and second through his commendable feats.
One of the first things to note in this poem is the importance of ancestry. The Geats and Danes meet mindful of the strong warriors they have descended from.
In Chapter Five, Beowulf first identifies himself by name, and his clan:
We are of Hygelac's clan; I am named Beowulf...
Hrothgar acknowledges Beowulf based on his heritage; he admires Beowulf as a warrior; he thanks God for Beowulf's desire to fight Grendel; and, he bids that Beowulf and his men be welcomed quickly as honored guests.
I knew him from his young days; his aged father was named Ecgtheow...he has the strength of thirty men in his grip and is bold in battle. The blesséd God...has sent this man...as a hope against Grendel's terror...Be quick, and bid the band of kinsmen come before me. Say to them that they are welcome guests of the Danish folk.
At the start of Chapter Seven, Hrothgar greets Beowulf by recalling the younger man's father, and his heroic feats...
To give us your pledge and rescue us at honor's call, my friend Beowulf, you have come to us. Your father's battle kindled a mighty feud when he killed Heatholaf of the Wylfings...
In the face of Beowulf's reputation, his heritage, and the feats his father accomplished, Hrothgar has—in a social and military sense—honored Beowulf the way one today would praise a person's resume. In all things, honor is the most important thing: to be honorable and treat others with honor—if they deserve it.
For example, in Chapter Eight Unferth (of the Danes) tries to criticize Beowulf—who as a guest, should be shown great respect. Beowulf speaks to Unferth's insulting words by stating why Unferth can act so dishonorably—:
What mighty things you've just said of Breca and his triumph, my dear Unferth, while you're drunk with beer!
Beowulf speaks with humility: saying he was permitted to be victorious:
...it was granted to me that I pierce the monster with my sword point...
Beowulf has no sense of ego. He "fights back" with words. He provides his credentials—how he killed "nine water-monsters with my sword." He delivers words as sharp as any sword, saying that if Unferth's sword was as strong as his boasting, Grendel would be gone. And that Unferth has shown what he is made of—murdering his brother...
...you were the bane of your dear brother, your closest kin, for which the curse of hell awaits you, regardless of your cunning wit!
In Chapter Ten, Beowulf notes that if Grendel fights without a sword, he will do the same; God will decide who wins:
I [am]...in no way weaker than Grendel. For this reason will I not give his life to the sleep of death with a sword...He has no skill...with [a] sword...mighty though he may be in his horrific feats. We shall...make war without weapons. Let the wise God, the holy Lord, decree success on whichever side seems right to Him!
Beowulf fights honorably—using his hands; his fate is as God decrees it.
In all Beowulf does, he venerates honor, is humble, comes to serve, and expects success if God wills it—not by his own strength. His service is greater than he is, or what he accomplishes—different from some of today's heroes.