Beginner Seller Question about GTINs

I am trying to sell some vintage toys that are new in the package. They have a UPC on the back but they aren’t registering in Amazon’s system, they have never been sold on Amazon. Do I have to purchase a new UPC for each toy?

I tried a couple barcode lookup websites and couldn’t find them on either.

I tried asking this during a call to Amazon Seller support but they seemed annoyed and didn’t really answer my question