It seems like realistic portrayals of people, places, things, etc is a very recent phenomenon (<500 years). Why is that?
For example, why is there not a realistic contemporary portrayal of the pyramids and what they were actually used for?
I think it's actually the other way around. In a way. Yes, there are more realistic paintings of people in places in the last 500 years or so, but that's because the means became more readily available and specialized training (apprenticeship) began to occur when civilizations no longer had to have every one farm for their entire lives, and free time began to appear. However, the trend of realistic paintings fades dramatically in more recent times with the invention of the photograph, since they captured people exactly as they were/are, more room for creativity entered the world of art. Theres a video on youtube that shows the evolution of women in art, and there is a distinct change of style in the later years.
After a little search I found some realistic portraits dating to apparently the first few centuries AD, and some really old portrayals of Jesus, and a bunch of stuff all older than your 500 years..? Just saying. EDIT* And Roman* Egyptian funeral portraits.