Your post could be paraphrased as "It's obvious X isn't helpful because X isn't ancient and X isn't helpful. Why do people do/use X?"

Please use better logic. Also, fetishizing ancient things is an impediment to progress.

The long term survival of the human species in the presence of something is (weak) evidence that the thing isn't harmful, but the logical inversion isn't true. That is, the survival of the human species for a long time without something is neither a valid argument for nor against that thing's benefit.