Well, justamom, you reminded me how much of a kid I still am! With the exception of building a fort and being an imaginary person, I have done all the things on your list in the past three years! (And the only reason I had to go back three years is cause that's the last time I went to a circus.)
My husband and I have thumb wars all the time.
Of course, I also collect My Little Ponies. I don't think it's so much that I act like a kid, I just don't want to lose those qualities that kids have that make life so much less stressful. But then again, maybe it's just because I have the worst long term memory of anyone I've met, and I honestly can't remember being a kid. Maybe doing these things reminds me that I once was a kid, even if I don't remember it.