I agree with the spirit of what you're saying but you go too far, ironically asserting without any supporting logic that the intelligence of homo sapiens has remained static for the last 2,000 years. But I suppose the disagreement hinges on what is meant by intelligence.

Here's a thought experiment: if you removed all technology (tools, writing, vast stores of knowledge) from a human child and raised them in this vacuum, would they be more or less intelligent? Would they understand their place in the solar system and the structure of the cosmos? Would they know how to protect themselves from sickness (germ theory)? Would their vocabulary and ability to express themselves be less or more?

Of course these questions don't have definitive answers and you can play the game the other way, arguing that modern humans would die in a couple weeks if transported back to caveman times.

But it's a poor model to view intelligence as some static property independent of technology, environment, gene mutation, sexual selection and all the other strings in the web of existence.