The movie is brilliant in that it depicts humans first relationship with a deadly natural world which has only recently been subdued by industrialisation. Today we have a conscientiousness about the preservation of nature, but for thousands of years nature has been our unstoppable enemy against which we must arm ourselves and prepare.
There's a reason why Satan appears as an animal in the garden of Eden. In myth and fable the supernatural has always commanded animals. In many primitive tribes the biting of and subsequent death of a villager was taken as a sign the person had committed sin and therefore had they been bitten..
Mankind in such crushing numbers has razed driven nature to the periphery, but your ancestors did not have romanticism for nature. It was filled with the magic of witches and voodoo and was to be destroyed and tamed.
The Witch gives flesh to the eerie feeling you get surrounded by forest with no civilisation and parking lots. It conjures our nightmares for the untamed person of nature who has surely sold his soul to the devil and rejected the clean and orderly world of God.