For the people where 24h time is normal …. Is that a more recent development it’s the ubiquity of digital clocks, or would people have also used 24h time with analog clocks, despite them not having a way to display that?

I’ve been born in central Europe in the 80’s before digital clocks became the norm. 24h was normal even then when writing the precise time. For example in TV schedules. When talking we normally use 12h but without adding AM or PM as it most often is obvious from the context. When it’s not then we add “in the morning” “at night”. Actually speaking time in a 24h format is very rare.