You might not understand how sophisticated and complicated chariots were. They were cutting-edge technology for their time—and they were considerably more than a wood box stuck atop wheels. The box was usually not even wood, which would've been too heavy, but cane or other sturdy plant materials. Think of the many things involved. What would be the best type of wood for the draught-pole, so that it was light enough but still suitably strong? What of the wood for the wheels, and how many spokes should it have? How many people should the carriage carry, what would be their specific functions, and how many horses should pull the device? How do you train the horses to do so? Et cetera.
Answering these questions has enabled scholars to understand how the chariot developed in the ancient Near East and how it spread—even it's been my own research experience that there's no universal agreement on who first invented the chariot. Answering such questions also enables us to identify the specific culture who used a given chariot, considering they tended to be unique in design to individual cultures.
So in summary, no, not all things are equal. Someone comes up with an idea and it spreads. All ancient Near Eastern civilizations—and the rest of the world's civilizations, for that matter—freely helped themselves to the ideas of others, and frequently improved upon them. The Egyptians, for example, invented neither the chariot nor the khepesh sword, but they adopted them to great effect.