[dragontamer]

> They didn't knew about bacteria and wouldn't have had the theory to explain why it would help.

That didn't stop say, the sterilization effects of silver from being widely known and spread across myths.

Fewer people got sick when they drank from silver cups and silver stuff. They didn't know a thing about bacteria, but enough people drinking from enough different cups and suddenly a pattern emerges that forms the basis of a myth or legend.

> We know that People generally knew about basic hygiene and applied it even if they lacked modern theory.

Soap and its effects to destroy common pathogens (viruses and bacteria) wasn't known... but "Hygiene" became a thing as early as 400BC Roman periods because of similar patterns.

The theories we have today summarize centuries or millennia of collective experience. Not the other way around. We don't need to understand bacteria to discover how useful soap, boiling, or silver/anti-bacterial surfaces are. Instead, we use our knowledge of "silver prevents sickness", "soap prevents sickness", and "boiling prevents sickness" to help us discover a grand theory of microorganisms / bacteria.