I think a huge part of this is the fact that as kids we had time, we weren't busy studying or working or doing anything "important" with our lives so we had the time to look around us and notice the little impressive things in the world, as adults we're always busy doing something. I think you can try to get better at noticing these things if you make it a priority and I don't mean that you have to prioritize it over work for example, but prioritize looking around you over, let's say, checking your phone. Basically try to find the time in your day, it will only take a few minutes of your day and the more you do it the more natural it becomes