I understand what you mean, I have the same feeling - everything is a but less vivid now.
I am no expert, but my guess that is happening because you have much more experience with the world now. As we age, the number of things that will be completely new to us becomes smaller and smaller. We just have more experience, and even if we haven’t seen/felt/heard something particular, chances are, that your brain still won’t be completely surprised - it will be able to find some experiences that you have which are close to that new thing.
But when you are a kid - there is a whole world of things you didn’t experience at all or didn’t experience enough to understand fully. That’s why everything was so vivid - there was a lot of “truly” new experiences.
Is it normal for a person to "feel" less as they get older?
I remember experiencing the world much more vividly when I was a little boy....