The Kuranda markets are a pretty good attraction. There's lots I didn't include in the post as it wasn't about the markets, but I'll write some more later.

There's also some other attractions in the immediate area like the Rainforest Station where they have animals and forest expeditions where they drive around in army ducks, amphibious vehicles, and then go into the Barron River and drive/boat around which is cool. They have commentary and stuff. I've done it and it's good fun.

That rail thing you have would be something fun for any five year old I think. You should make it happen.