It is easy to understand why scientists mistook them for stooped, hulking brutes with a vacant expression. Their skulls were low in front with a heavy ridge of bone above their eyes. They barely had any chin at all. They had a brain capacity greater than modern humans. This does not mean they were smarter than we are.
Intelligence depends on size and organization of the brain.
Studies show that their vision was probably better than ours, but their language was not as developed and they couldn't think ahead as well as we do. The Neanderthals were great hunters. They hunted large animals such as mammoth and woolly rhinoceros with little more than fire hardened wooden spears. There is no evidence that they used stone spear points, but they did chip stone scrappers off flint cores. Neanderthals buried their dead, including small children, with food and tools, probably indicating some kind of religion.