I was raised Catholic, and I'm also a compulsive reader. (The first month I spent living in the same house as Mr. Oniya was very... enlightening.) So, my exposure was a bit more than the 'average' Catholic. Even so, I've seen books of 'Favorite Bible Stories' in book stores, and you get things like Jonah and the Whale, Noah's Ark, the Nativity Story, Daniel in the Lions' Den, David and Goliath, Samson and the Philistines - those are the ones I'm just pulling out of the air. You definitely don't get things like the Song of Solomon - which is actually some fun reading, as a dialogue between two lovers.
Basically, what I'm saying is that there are certain stories that are definitely moral lessons, and those are the ones that someone who doesn't study it, or go to services (you get some of the less exciting stuff during the readings) is likely to be familiar with. It's the same way that most people know a handful of Greek myths, but wouldn't recognize many of Aristophanes' or even Ovid's works