I appreciate your time and explanation. I'm really trying to understand the POV here, and I feel like we're veering away from my original confusion, which was around "Try defining data in C. Try extracting data from that data you've defined in C". I'm assuming your statement would be meant to apply to other common languages without s-expressions, but maybe I've misunderstood.

I don't get why Lisp's s-expressions are much better than using arrays/tables in another language, such that they are a justification for using the language. Are they only significantly superior over a language with only arrays, like C? What's something that is made significantly easier by an s-expression than by arrays/tables?

To make s-expressions language-agnostic, wouldn't you need libraries in the languages to convert between the s-expression as it exists in some specification, and the language's native data structures? This doesn't sound all that different from JSON at this point, or a much more complex specification that defines the representation of all kinds of types, like dates.