Explaining cybersecurity to someone from the 1920's

My brother or sister, they didn't have antibiotics. Electricity, hot water and cars were a little bit inconsistently available depending on where you lived. Airplanes and highways were a rare and exceptional thing to see to almost everybody. The first vaccine was twenty years in the future.

Bakelite was invented by the 20s, but in 1924 I think it would still have been known as "artificial amber" and no one would have known what you were talking about if you tried to talk about plastic.