Over time, the word evolved into the Italian "carico", which meant "load" or "burden".
This Italian word was then adopted into English in the 16th century as "cargo", initially referring to the load carried by a cart or wagon.
Eventually, the meaning of "cargo" broadened to include any goods carried by a vehicle, especially ships and planes.
So, essentially, the word "cargo" traces back to the idea of a load being carried by a wheeled vehicle, which is a fitting origin for the word given its current meaning!