You appear to be assuming that painting something with a brush is substantially more time consuming than painting something with a drawing tablet. Other than maybe mixing the paint and letting it dry, the effort seems to be able to same
That is not the case for digital works. If we get strict about it, everything apart from the original file sitting in the artists' computer disks are copies. The file you downloaded after purchasing your "original" is a copy.
But well, whatever makes people happy.
Yes, and a copy of a digital work still has some value, but there's only one NFT that the artist issued to represent ownership of the digital work. These are precisely identical stories. Even if you could create a physical copy of a physical painting with arbitrarily high fidelity (perhaps at the atomic level), there would still only be one painting that sat in the artist's studio, and I suspect the art world would still only value that one as the original.
In other words, the fidelity with which one can create copies of an original work is irrelevant to the determination and valuation of originality.
However, if the molds are still available and another can be cast and finished, then no.
Still a specific instance of an unoriginal item might be special. It could have been painted post-casting by someone famous, or survived a war or shipwreck, and so forth. Originality is now no longer a distinguishing aspect of the sculpture's value.
A marble sculptor shouldn't be valued more than a digital sculptor, its really just about time and effort either way.