>>52604399The dex entry for Magnemite in Gen I mentions that it's hatched, which was changed to born later. That implies it's not man-made on top of that they appear in the flashback for the kalos war 3,000 year ago. The fact is that magnets and screws in Pokémon occur naturally in nature. That's why Sandy Shock still looks like it has screws and magnets since those are the base of Magnemite's design and it's prehistoric form would still retain those naturally occurring elements.
