Final answer:
The theme developed in The Hobbit when Bilbo uses cunning to rescue the dwarves from the spiders is that heroes come in all shapes and sizes.
Step-by-step explanation:
The theme developed in The Hobbit when Bilbo uses cunning to rescue the dwarves from the spiders is that heroes come in all shapes and sizes. Bilbo, who is initially portrayed as an unremarkable hobbit, demonstrates bravery and resourcefulness in his actions. By using his wits and intelligence to outsmart the spiders, Bilbo proves that one's size or appearance does not determine their ability to be a hero.
Learn more about theme in The Hobbit