It seems unlikely to me that there exist concepts that can't be at least broadly conveyed via some combination of those. My intuition is that existing human languages cover, with their descriptive power, the full range of explainable things.

My intuition is the exact opposite.

it seems unlikely there exists a law of physics that cannot be expressed as an equation

I can totally imagine that some models are not reducible to equations, but that's not the point, really.

Even if I'll never have the insight that lead someone to write it down, if you give it to me, I can use it to do things.

Unless this "use" requires more brainpower than you have... You might still be able to work with some simplified version, but you'd have to have transhuman intelligence to "do things" with the full equation.