Of course one might argue that even if LLMs are capable of ideation and conceptualisation without natural language, doesn't mean humans are.
But the fact that up to 50% of people have no inner monologue seems to refute that.
Can you imagine the (intentional) creation of a program entirely without language?
Or, I suppose, if you're ok with it not being intentional, you can program via an evolutionary algorithm - is that what you have in mind?
Math is all about abstract shapes and properties, for me. So is much of programming.