Also, Henry, who was born in Phoenix, AZ, is not under the power of the curse. Although he lives in SB, he was aging in a town where time stood still (until Emma started the clock again). Henry believes in magic, because of the book and because he is a child who was raised amongst fairy-tale characters (though most of them are cursed and don’t remember).
Do we know how old Henry was when Regina adopted him? Could he have aged outside of Storybrooke, then stopped aging once he came to Storybrooke? Just wondering.