We don’t know a lot about Emma’s magic. People are embellishing the little we know that has been said in the show and interviews. We know she has powerful magic, is the child of true love, but that her role as savior also has something to do with it, though it might not be the limit of it. Just as the curse might go beyond Rumple’s original intentions for having it cast, and certainly Regina’s in casting it.
Jane said she learns new things in the writers room all the time. Henry may or not be magical, and it may or may not be based in being the child of true love. Emma TRULY loves Henry. That’s cannon and maybe a mother’s true love like that is enough to spark magic? We have no idea.
Emma being special doesn’t mean Henry can’t also be special or a hero. In fact, he’s already been written as a necessary link to her destiny.
“If I had a world of my own, everything would be nonsense. Nothing would be what it is, because everything would be what it isn't. And contrary wise, what is, it wouldn't be. And what it wouldn't be, it would. You see?” -- Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass