FWIW, is-arrayish is primarily an internal dependency. The author (Qix) depends on it for the packages that actually get used, liked color and error-ex.
Yes. And npm shows 1500 direct dependent packages. [1]
Vast majority are nothing. No stars, no downloads.
(IDK why. What I do know is that if you crack open the node_modules for any real project, is-arrayish will be there only because of one of the Qix packages.)