Best Of

Copyright is what legally determines ownership of your work - you automatically own the copyright to your work as soon as you create it - as long as you have proof that you've created the artwork. Generally, this would be the original source art time stamped with date of creation, but could also be credit on a commercial product, as well as known publication of the work - on your artstation page, social media accounts, including work in progress shots and things like that.

The crucial thing is you have to protect that copyright if someone infringes upon it. This means sending C&D/copyright takedowns in any instance that you see art theft. And if that doesn't stop the person who is infringing, you'll need to take the person to court to resolve the matter - and pay all of the legal fees etc.

Minting an NFT doesn't protect you in a legal sense or make it harder for someone to steal your work. It may make it easier to prove that you're the original owner of the work, however, this doesn't mean much unless you're prepared to file suit against the other party. Even in that case, it's doubtful whether a court would consider an NFT certificate meaningful or relevant.

Of course, I'm not a lawyer, so you should speak to a professional if you have concerns about art theft.