C isn't a simple language, really, because it has a ton of implicit assumptions and inconsistencies, undefined behavior and all the failure modes you have to keep in your head at all times.

It's not that C is simpler, it's less expressive.

I don't think this answers parents question though, which is what does it mean for a language to be simpler? I think that's a good question. This is just a list of examples.

It almost seems like simple is a bad concept applied to languages because what's simple and complex is the idea you're trying to express, accurately, in its totality - not necessarily the language.