The classic Hero's Journey begins with humble beginnings. This meek and predictable life is what makes the next step, the call to adventure, so terrifying. The 13 backgrounds presented in D&D's Player's Handbook covered a lot of possible backstories, but the sense of humble beginnings was missing. What if there were another thirty or more backgrounds to choose from? What if each one had a uniqueness that added flavor and personality to your player character? What if your background wasn't the thing you chose at the end of your character design, but was the life you were Called To Adventure from?
These new backgrounds are balanced evenly against the existing ones. The features that each one benefits from are minor boons but useful in everyday game play. Proficiencies gained and equipment are likewise included in the balancing to prevent power-gaming and to make the world's greatest roleplaying game more fun for everyone.