Maybe you are right, they didn’t need a cart, maybe. Here is the point you are missing. Your whole argument is based on a lack of necessity. The fact is however that not all inventions are born out of necessity. Some inventions are born out of convenience, or curiosity, or novelty.
Oh yeah carrying one bag somewhere definitely requires a cart.
The wheel was invented because people had to travel dozens or hundreds of miles. Not a hundred yards down to the river and back.
Maybe you are right, they didn’t need a cart, maybe. Here is the point you are missing. Your whole argument is based on a lack of necessity. The fact is however that not all inventions are born out of necessity. Some inventions are born out of convenience, or curiosity, or novelty.
Ever see a modern offroad vehicle try to drive through the jungle?
Sometimes shit doesn't get invented because it's not practical