What is the validity of Ayurveda in the face of modern medicine?
The issue is that the Ayurveda texts were orally passed down for millions-billions of years from Vishnu (who orally passed it to Brahma, and so forth):
Charaka Samhita - At first, Prajapati received the Ayurveda in its entirety as recited by Brahma, from whom the Ashwins received it, and from the Ashwins, lord Indra received it fully.
So this means the knowledge of Ayurveda hasn't been "verified" or "updated" in billions of years:
This tri-aphorismic, continuing from time immemorial and virtuous knowledge which was known to Brahma first.
Humans evolve and can change biologically, diseases come and go, microbes mutate and acquire new resistances, materials and new technology offer alternative treatments that get improved over time. But since Ayurveda doesn't get updated (since it's an oral tradition), contemporary scientific inquiry into medicine is superior to Ayurveda since it's based on present-time, direct perception of facts, and it's a living tradition that gets improved over time as opposed to a static (oral) tradition.
Ayurveda was the only option in ancient times when they didn't have the concept of modern science. But now, anyone would choose direct perception of facts over an oral tradition of recollection of facts.
My question is, does Ayurveda truly contain eternally valid knowledge regarding human health and medicine? What indicators does it give to show this?