eg in ancient Egypt. No calculator, nothing, only brain and muscles and physical basics. How smart were these engineers from then in comparison to today?
At that time, humans had to be extreme efforts to plan calculations and structures. Today you can theoretically type everything in the PC (exaggerated)
The IQ is a heavy thing. You do not know yet what intelligence is how to measure them and tests often have potential sources of error, such as unilateral questions or trainability. The people at that time had partly excellent cognitive skills is out of the question, but whether they are smarter than today is difficult. In addition, you have to watch who you compare each other that e.g. a then scholar more on the box has as a stupid person today is logical.
People were certainly not smarter than now. Sufficient quantities of food is relevant to the growth of the brain and formerly scarce ...
No, that was the same. butPreviously, there were significantly less harmful things for which people could mislead their intelligence.
Most people were illiterate. You make the mistake of closing the Einstein's time on the entire population. And your statement in the end is not right. Student a natural science / engineering, then you do not say anything like that anymore.