Is sodium percarbonate artificial?
Yes, it is artificial. Sodium carbonate is a substance that occurs in nature, even though any of it is most likely manufactured.

Sodium percarbonate, on the other hand, does not occur in nature and it has to be manufactured. It is an oxidiser, and oxidisers don't occur in nature normally. That's a problem for you, because oxidisers (aka bleach) are desired in laundry applications.