Your question seems to imply a universally held belief that Americans are the smartest people in the world. This is a broad generalization that isn't supported by any comprehensive or universally accepted metric. Intelligence, as measured by IQ tests or other academic indicators, is widely distributed among populations worldwide and is influenced by many factors, including cultural, environmental, and genetic influences. It's important to understand that the idea of "intelligence" can also be subjective and multidimensional, encompassing areas such as creativity, problem-solving, emotional intelligence, and practical knowledge, among others.
there is no scientific consensus or data that definitively places Americans—or any other nationality—as the "smartest" in the world. People from every part of the globe have made significant contributions to science, technology, arts, humanities, and countless other fields.
Furthermore, defining a group's intelligence by nationality can lead to stereotyping and other harmful biases. It's more constructive to recognize the potential for intelligence and creativity in all people, regardless of their nationality.