Mesopotamia invented Bricks, they made them out of mud and straw. Bricks helped people have stronger and more protected shelter. When a big storm is coming up would you want to be in a house made out of straw or bricks? I would want to be in house made out of bricks. If you had money and food where would store it from storms and criminals? In a straw house? No, I don't think that would work. In a BRICK house!
The chariot helps people get to places faster. A horse would always carry it also. If you needed to carry for example 200 pounds of bricks to a building area will you carry it back and forth? Or will you put it all on a chariot and just drive there once and get all the bricks at one time. The chariot really helped people get to places faster also. If it takes 2 days to get to the ziggurat not very many people will go their but since people had chariots they went their more often. Also people could get food and help faster.