Here’s the rub though - the blockchain only proves that the NFT is authentic as claimed. But an NFT by itself doesn’t convey copyright so it’s really not necessarily unique. The creator of the image/art holds the copyright and if it doesn’t transfer, the NFT buyer can’t be sure the creator won’t (legally) duplicate the image in NFT form or otherwise. And without copyright the NFT owner can’t legally duplicate it or make derivatives from it, nor can the NFT owner act against others who have illegally duplicated it.
NFT is not intellectual property and unless the IP is acquired, it simply means you own that singular piece, and can authenticate it.