What do you think magic is a special ability or it is a learnable thing?
Because Emma was born with magical abilities, but Cora and Regina learned the magic.
So anyone can learn magic in Storybrooke or in the Enchanted Forest?
I think a person needs to have magical essence in them in order to learn or cultivate their magic. Rumple could see that Cora, Regina & Emma have it. Perhaps Charming & Snow have a touch of magic too based on their psychic connection. Perhaps everyone from EF does, they just don’t realize it.
I was just thinking about this yesterday when watching WL and while watching a Christmas movie called “Christmas Spirit”. Amara saw the magical essence in Jafar, therefore she was intrigued by him as a child and didn’t kill/harm him in the street. “Christmas Spirit” was about a woman, a writter, who had a magical essence, the Christmas Spirit, that she was able to use to help the citizens of her town out of their financial troubles while she was in a coma. Her neighbor lady was the only one who could see the writter, told her that the gift was special, and helped guide the writter on her journey to back to the living. Otherwise the writter was just an ordinary person in the real world.
Nothing is impossible on OUAT. Everything has a way of repeating itself. Keeper of the Keeper tread: https://oncepodcast.com/forums/topic/official-keeper-thread-3/#post-217924