When kids are days, weeks, months old, they're constantly experiencing new things. That's the first tree she ever saw! It's amazing to experience the world through them.
When they're a couple years old, you see them learning and connecting and developing a unique personality. I love it when my two year old picks up on things that I missed, or teaches me something. And it's kind of awesome to be someone's superhero for however long this lasts.
I don't know how it goes after this but so far the trend has been that they get more fun as they grow...