Hm, I'm not quite sure. I feel like, as other people have said, I was a lot less inhibited when I was younger, since I definitely came up with all sorts of creative story ideas. Looking back on it though, a lot of them were just that—ideas. I rarely wrote actual completed stories, ignoring major plot points and focusing more on random filler.
So, yes, I guess I had an easier time coming up with creative concepts when I was younger, but also no, because I had a harder time actually putting together a full story. I guess that's why most of my stories are adapted from stuff I came up with as a kid: I had the ideas back then, but now I have the ability to actually do something with them. 