In time hands were used to make simple tools out of pebbles. Another difference between humans and apes is the size of their brain. Differences in brain size are especially obvious when we compare the size of the brain to the size of the body. On average, humans weigh about 140 pounds and have a brain size of 1.4 quarts. A chimp's brain is about 0.3 quarts.
Chimps weigh about two thirds of what the average human weighs.
This is not a big difference. Let's think about another ape, the gorilla. Gorillas weigh twice as much as we do, but their brain is only a third of the size of ours. Clearly, we have more brain volume per pound. Now, people don't have the biggest brains among mammals.