Except what we get with the ancient records regarding willow bark were just what we’d expect with folk medicine: anecdotal claims that it treats a wide range of ailments without any proposed mechanism of action.

It wasn’t until willow extract was actually made into a pharmaceutical that it became anywhere near useful. That willow tea you’re imagining ancient people drank didn’t actually exist and if it did, they were not getting enough salicylic acid from it to equal even a single aspirin.

https://theconversation.com/hippocrates-and-willow-bark-what-you-know-about-the-history-of-aspirin-is-probably-wrong-148087

In short, aspirin follows the above rule: alternative medicine was proven to work, and then became medicine. But the end result is far detached from how it was used thousands of years before it was actually shown to work.