It is possible that you have misunderstood the concept of "intelligence". Many people often mistake intelligence for having a vast amount of factual knowledge. While it is true that intelligent individuals tend to possess a significant amount of information, the mere accumulation of facts does not necessarily equate to intelligence. Conversely, lacking knowledge on a particular subject does not make someone less intelligent than someone who possesses that knowledge. In the age of the internet, anyone can surprise someone else with a random piece of information.
Intelligence is actually a cognitive function that aids in the process of analyzing and comprehending data to find solutions or gain a better understanding of a problem. While having relevant facts is helpful in this process, it alone cannot lead to answers or comprehension if the individual lacks the internal cognitive ability.
For example, imagine the least intelligent person in medical school who puts in great effort to memorize all the necessary anatomy to pass the class. Despite this accomplishment, it does not necessarily make them more intelligent. However, there is evidence suggesting that grappling with challenges, like memorizing anatomy, could improve problem-solving abilities (another aspect of intelligence). Nevertheless, when faced with a different problem that requires intelligence, their knowledge of anatomy will not aid them. Their problem-solving skills, or intelligence, remain unchanged.
So, what sets highly intelligent individuals apart from those who are less intelligent? Perhaps it is their understanding that they have the capability to solve or mitigate nearly any problem that comes their way. (Unless they lack self-confidence, that is.) (However, over-confidence is not a characteristic of intellect; it falls under the traits of humanity such as pride and humility.)