I tend to read lower middle-grade, but my gut is telling me you're right, that's way too repetitive. I'm thinking of two books my sister and I loved as children. We each took one when we moved out because the books were pretty much THE SAME STORY.

It used to drive me nuts as a kid, but I think many writers start with a repetitive premise and then throw monkeywrenches in it to make the story interesting. This early in the morning, the only title I could think of was T.A. Barron's The Seven Songs of Merlin. The main character starts out with a straightforward task: learn seven magical skills and restore health to the island. It even levels up like a video game every time he gets a magical skill. But life—and the character—keep interrupting this task. He takes a detour to show off his magic and almost kills his mother, he has to go on side quests to heal his mother, he tries to skip steps with disastrous results, etc. And that's one book in the series. If you look at the whole series, you have a very similar premise for each book (it's a quintet): Magical island is threatened. Wizard boy/chosen one is the only one who can stop it. He has to conquer his hubris to successfully save the world. But the threats are many and varied and every single time the MC learns a devastating lesson which makes him far more palatable of a character in the next book. (I love the series, which is well-written, but am not a fan of the MC, sorry for the snark.)

So what I'm suggesting is, you could start out with your premise (which, as usual, is incredibly creative—seriously, how do you come up with this stuff?!), but then interrupt it and vary it up to make it interesting.