I still don’t understand what is “historic” about 99% of artifacts, but that’s beside the point I guess.
My theory is that because artifacts were initially created by the Thran, an ancient super race, all artifacts are considered historic. For example, Misha and Urza learned a lot from their archeological studies of Thran artifacts.
Jhoira's Familiar looks mana expensive, as many suggested already. But why not? I remember when Lion's Eye Diamond was considered the worst rare, if not the worst card. And look who is on the Restricted list now.