No animals to pull carts. Wheels weren't that effective without animals. They did have wheels on children's toys in at least some of the cultures.
The only animal that makes my wheelbarrel go is me...puzzling that they did not figure that one out.
That child's toy is mystifying. Perhaps it was not a child's toy at all, and perhaps it did not originate in South America but was imported from Egypt. It would be amazing if such a capable civilization did not instantly make the leap from that object to the idea of animal-drawn carts at least. They had roads, and probably beasts of burden, but why such roads if they did not use wheeled vehicles?
wheels without animals to pull the carts is difficult. wheels without animals to pull the carts in mountainous and rocky terrain are pointless except on children's toys.