If I may piggyback on your question: isn’t it only the hash of the digital asset that is unique and that you own as a NFT (e.g. an ERC-721 token wrapping the hash)? So if I change a single pixel or compress the picture with a slightly different setting, I get a new hash and can upload it as a different NFT. At that point you need to compare the NFTs and decide whose claim of true progeny to trust with things like original owner address and timestamps. Or am I missing something?