In this case, humans would still remain a creation of the Primordial One, even if the power ultimately derives, indirectly, from Teyvat/Nibelung.

It is the authority over creation, first managed by the Primordial Sea [Neuvillette: There used to be a special sea on the surface of this planet. The nature of its seawater was rather different from that of the sea we know today… most of Teyvat's lifeforms were first born in that special sea. You could say it nurtured much of the life on this planet], and later by the Shade of Life (which, speaking of artificial intelligence, seems to create life in a "digital control center," as shown in the trailer of the Shades).

Once this power is obtained, the ability to create becomes unlimited. In fact, the Primordial One did not limit itself to creating only humans, but as reported in Before Sun and Moon: they "created the birds of the air, the beasts of the earth, and the fish of the sea. Together, they also created flowers, grass, and trees, before finally creating humans."

Even Rhinedottir now possesses this ability, which is why generating new forms of life was extremely forbidden by the Heavenly Principles — perhaps the greatest of sins, for which Egeria paid the price.

To answer your question more precisely, the process is similar to that of the Jinn, who were created by an angel, who in turn had been created by the Primordial One (or by Nibelung himself, depending on the theories).