Unlike some other big deal heroes, Deucalion didn't save a girl by slaying a gigantic monster or anything. He did something even more impressive by saving the entire human race. Instead of lifting a sword, though, he lifted a hammer and built the floating chest that saved him and his wife, Pyrrha, from the Great Deluge sent by Zeus to drown the wicked Bronze race of humankind. After the flood, Deucalion and Pyrrha were able to reboot humanity by throwing some magic rocks over their shoulders. (Yay for magic rocks.)
Deucalion shows a lot of wisdom when he listens to his dad, Promethueus's warning about the coming flood. If he'd ignored his dad's warning, he and Pyrrha would've drowned along with all the other human beings, and all humanity would've been completely eradicated. Deucalion stands out from the rest of the humans of his day, because he's not all hardcore and brutal, and he respects the gods.
Deucalion proves his piety by giving thanks to the gods as soon he and Pyrrha land on Mt. Parnassus. It's probably a really good thing for Deucalion that he was so respectful of the gods. We're guessing that if Zeus didn't approve of Deucalion and his wife, no itsy bitsy boat would've been enough to save him from the flood. Like his Judeo-Christian counterpart, Noah, Deucalion is the one worth saving, the one whom Zeus hopes will get mankind started back on the right path again.