it is still really unclear if the Curse was already in existence before Rumple or if he created it from scratch
That is true. I was going off the fact that Rumple had said he created in the episode A Land Without Magic. I forgot about the convo between Blue Fairy and Rumple. I hope they address this in S3 as well.
But like I said in my orignal post, it’s a crazy theory! Rumple probably had nothing to do with Neverland, but it is neat thought because he has had his hand in most other fairy tales as we have seen 🙂