we think of cavemen as stupid right?

I would say uneducated rather than stupid. Just because you don't know something, doesn't mean you haven't got the brains to learn and understand it.

Cavemen are smart for their time. They already mastered some laws of physics and apply them to their daily life. For example, they can make a projectile that maximizes their power through a leverage system using less energy. They are also capable to make tools that assist in their life. Ours is not all different, they are just made from synthetic materials instead of rock

They took us to the point at which we live now. That's pretty smart. They were incredibly strong and resourceful, or they'd have gone the way of the dinosaur! I've always wondered how much of what we think we know about cavemen has any relationship at all with reality.

I don't think we consider them "stupid", I just think that they're more primitive than us. We take reading and writing as a given - something almost everyone knows - but they didn't know that it even exists. I don't think that this is because they were stupid, it's just because many of the things that exist today didn't exist back then and were yet to be discovered. They made use of what they had. They took the little tools they could find and managed to find a use for them. I think it's pretty amazing how they made a living just based on simple objects that they thought the uses of. Their minds weren't as advanced as ours, but this is only because they didn't have the same way of thinking as us. They were, after all, only at the beginning of evolving the world into what it is today. They weren't able to look at objects and immediately know their use, but they had to try different things in order to figure it out. I don't think cavemen were "stupid", but I do think they were very primitive compared to us. =P