Just to keep the record straight, the Borchardt C-93 dates to 1893. It wasn't plastic, but it was striker fired. I'm not sure it was the first.Glock wasn't the first to produce a striker-fired pistol. H&K beat them by 12 years in 1970 with the VP70.
Other early striker fired pistols include (but are not limited to) the Browning 1910 and several Walther pocket pistols.