> before the 50s and 60s everyone knew you should cover up and women wore bonnets. That too much sun was bad for you.

I'd say partly true, mostly false. As sibling comment mentions, much of this was driven by fashion and class etc. and not from some fundamental understanding of damaging UV exposure.

Furthermore there was research that was trendy at the time called "heliotherapy" [0] where all sorts of diseases were believed curable by sun exposure, including smallpox, TB, etc.

0: https://en.wikipedia.org/wiki/Light_therapy#History