It seems pretty obvious to me that any useful definition of intelligence (if we even need one to make progress) is going to have levels. We're not all on equal

It seems pretty obvious to me that any useful definition of intelligence (if we even need one to make progress) is going to have levels. We're not all on equal footing at every task, and we're not even on equal footing in our abilities to _learn_ a particular task. It may be a parsimonious position but it seems totally at odds with reality?