How often have you seen a child simply staring in wonderment at something completely mundane. At least to you. But for that child the scene is full of new and amazing colors and textures and forms. To you it might be just another tree. But to the child it's a TREE!
I think it's at least partially a case of preconceptions. Have you taken a walk with a camera, only to return with little or nothing to show for it? Perhaps that is because you subconsciously already "knew" what picture you thought you wanted to make. And you already "knew" how the things you observed on your walk would look when photographed. If you didn't see a match in advance, you skipped it and kept walking. Or tried to force a square peg into a round hole.
Children see everything around them with a deeply-felt original astonishment. Sometimes I think the adults need to try to regress back to that a little bit, instead of drifting further away from it as the years roll by. It might make a difference in your photography. It would definitely make a difference in your life.