Intelligence is characterized by three main features. Firstly, it is the ability to cognize, explore the world around us. Secondly, this property is present in all types of mental activity, and not just some kind of ability. And thirdly, it is mainly an innate quality that is inherited (or not inherited) from our ancestors, and the environment and personal experience affect the degree of intelligence to a lesser extent.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.