What universal themes are conveyed by the descriptions of battles between beowulf and grendel and between beowulf and grendels mother?

Heroism- Beowulf's heroic tendencies are exemplified by the two scenes in the narrative than any other scenes. His actions are fearless, and brave. They seem to allure to the importance of facing attitudes like him in a fearless and brave manner.

Good vs. Evil - the author describes Grendel and his mother as dreaded monsters. Beowulf; who overcomes them through different approaches, is describes as the quintessential human being, who is honest, honorable, loyal e.t.c. albeit with quasi-superhuman powers.  

Bis correct you are right