Composition of intellectual achievements from ages past might not reflect the intelligence of ancient societies, but perhaps the inquisitiveness of ancient societies does. Why were they inquisitive? Because their world was full of endless wonder, untapped resources, and even superstition. Their very survival depended upon the accumulation of contemporary technologies.
Today, curiosity has been quelled by prior knowledge and stimulation. Thus, we have no reason to be as innovative as we were in the past; and I suppose we appear less intelligent as a result.
Why bother conceptualizing another Great Pyramid when you have Chuck E. Cheese down the street? Why bother mapping the world when you have Google Earth at your fingertips? Why bother achieving anything?
Today, one does not need to be technologically progressive to survive. One just has to perform mundane procedures.