Why did the little prince believe the people of earth have no imaginations

In Antoine De Saint-Exupéry's The Little Prince, one of the main characters, who is the little prince, says people on Earth have no imagination because after he encountered the snake, the flower, and even when he climbed a mountain, no one answers him his question regarding the location of the men there. And when he asks where the men are to the mountains he gets an echo for an answer. Therefore, he thinks people have no imagination because they repeat whatever one says to them. He concludes by saying: "On my planet I had a flower; she always was the first to speak ..."