David is the creative power God buried in every man, and the giant he goes out to meet is the whole weight of the senses defying you, the massive fact that seems too large to answer. The reward set for the one who kills him is not a legend about a soldier. It names what happens inside a person who lets his own imagination overthrow the appearance that mocks him: riches, union, and a house set free.
Saul is the sleeping state that cannot recognize its own offspring, the mind still ruled by what it can see. To make the father's house free in Israel is to release the whole self from bondage to circumstance once the inner power has conquered. The man does not defeat the giant with strength. He defeats it by daring to assume the state the giant said was impossible.