The best description of the hero archetype in literature, as exemplified by Sir Gawain in the passage from "Sir Gawain and the Green Knight," is:
It signifies a character that is clever, resilient, and that faces great challenges.
This aligns with Sir Gawain's willingness to take on the challenge presented by the Green Knight and his desire to prove himself as a valorous knight, despite recognizing his own perceived weaknesses.