It is necessary to apply face cream on natural skin?

No, it is not necessary to apply face creams on natural skin as these might give you some side effects which occur by applying cosmetic creams. You should always prefer to use natural ingredients that are present in our kitchen for your skincare treatments.
Turmeric, Honey, Clarified Butter, Fresh Fruits, Milk, Gram Flour, etc are various natural products that can be replaced by more expensive creams out there in market.