Simplify the following text for a Grade 8 native English-speaking person.
Original: The cover is a metaphor for Bella 's progression throughout the entire series ; she began as the physically weakest player on the board , the pawn , but at the end she becomes the strongest , the queen .
Simplified: The cover of Breaking Dawn is a metaphor for Bella 's changes during the entire story . She began as the weakest ( at least physically , when compared to vampires and werewolves ) player on the board : the pawn .