Yes, Aldia created him after experimenting with the giants Vendrick captured. Before the Scholar of the First Sin was released Ancient Dragon was assumed to be Aldia himself but it turned out it was just one of his experiments.

I mean that makes sense since I hear you don't get the actual dragon soul from him. But then what is he? Did Aldia create him as well?

He is not what he appears to be, do it for Vendrick.

Lay a hand on him and he will give you a good reason to uninstall the game