There's a difference between opensource and proprietary works. For example, I use "PouchDB" in some of my apps and their code is opensource, but what I make with it is not opensource.

It's one thing to make something similar, and there are often more ways than one to do that, but how would one know if AI created something unique or just copied some human's copyrighted work and presented it in a response?

TBH, I have not dug into how it works, but I did ask it to show me how to make something with PouchDB.js and it looked like it was pretty much a copy and paste from their website. That is not really an issue, but it did not attribute that code to Pouchdb.com. And, to be fair, I did not ask where it got it. But it seems to me that if they got it off the PouchDB.com web site it should tell us and provide a link to the original source.