Why did the first settlements appear on the banks of rivers and at the intersection of trade routes?

In ancient times, when people became sedentary and began to found the first settlements and civilizations, they chose places near the source of water or at the junctions of trade routes, because at that time, agriculture could only be developed on the banks of rivers due to the lack of irrigation systems. This can be seen in the example of such ancient civilizations as Egypt, the countries of Mesopotamia. Cities were built at the confluence of trade routes, because there, residents of different regions exchanged goods, so the market was their center.