Why does every word in English have to come from somewhere else. New words are invented all the time, duh, noob.
The reason why is mostly a bootstrapping problem. The purpose of words is communication, and it's a lot easier to adapt an existing word to a new purpose that it is to just invent some new pattern of sounds and convince people to start using it. It's easier now with mass media, but prior to that, nearly impossible.
For every "Zyrtec" (which still plays on "tech") you have "Claritin" ("clear/clarity") and others.
It's hard to find a word that is a truly original coinage not based on any existing words.
I’m thinking of things like “a parliament of owls” or “a murder of crows”.