Oh I definitely think certain things about the world should be added by the narrator, so generic descriptions that most people of the Sword Coast would know (but not something someone new to D&D would know).
"Selune, the godess of the Moon...." "Shar, her evil Twin sister..." "The Blood War, the eternal struggle between demons and devils..."
They can easily weave more of those kind of lines to get the player up to date.
