I just read the Beowulf story in depth. I have one opinion question? Anyone?

Disagree. Because when you meet Beowulf in the poem, he's already a grown man, not a boy. And honestly I don't see any personal growth in him other than that he takes charge over Heorot, which isn't really a growth rather than a gain in status. The story is really more of a chronicle of Beowulf's life in terms of being a hero. The tale was essentially used to outline the belief system of the earliest English people; you had to be a warrior, you had to be tough, you laid your life down for your lord and land, etc.