What the caves of lascaux suggest about early human society?

That's a very interesting and profound question because we cannot know what they believed or how they organised themselves. It is very likely that they lived a tribal, often nomadic life as hunter-gatherers, and cave art usually does show either hunting scenes or large animals that could have been killed and eaten.

A common interpretation, and it can only be an interpretation, is that the paintings had some spiritual / ritual role associated with hunting; and that since their prey animals were obviously large ones (from the pictures), they had to hunt in well-organised groups in order to catch the animals. Further, they chose large animals in order to feed sizeable families & tribes; and for useful yields of furs and bones.