Are we? I thought we had "general intelligence" = "mental ability to solve general problems".
Trying to measure that is difficult because we humans have specialized for certain types of problems and like to measure human-like intelligence (where for example things like language, vision, hearing seem like they ought to be easy, and math might be considered either hard or trivial). Eg given a verbal or hand-written word math problem, the human would likely have no trouble with anything but the math, but a computer would have no trouble solving the math but fail before even starting -- what the words are, what the words mean, trivial math problem. Humans have, for example, specialized portions of the brain to recognize faces, or to separate out voices from other sounds, not to mention giant portions of the brain dedicated to each of the senses, which makes those sub-classes of problems basically effortless.
Even when problems can be reduced to mathematics, it wouldn't be fair to measure the difficulty of a problem by computational resources required (eg matrix multiplication) vs what might be called cleverness (eg constructing a proof, or maybe finding a pattern) which seems impossible right now to measure. As I understand it, computers now have comparable computational resources to humans (depending on how flops are compared to synapses) but are vastly lacking in programming. Keep in mind that a human's basic programming and schematics is only 800 MB for both hardware and software.