> not close to or identical to any programming language other than Lisp.
It's close to the Lisps, Scheme, Racket, Clojure, and many others.
You are correct that the popularity of Ruby, Python, and JavaScript has eclipsed the popularity of these languages, and so the popularity of JSON has eclipsed that of s-expressions.
It should be unsurprising that languages which have adopted Lisp's syntax/programming model to a larger degree will also naturally find Lisp's syntax/programming model to work for them, while languages that haven't... won't.
It's close to the Lisps, Scheme, Racket, Clojure, and many others.
You are correct that the popularity of Ruby, Python, and JavaScript has eclipsed the popularity of these languages, and so the popularity of JSON has eclipsed that of s-expressions.