That's not necessarily true. Anthropologists say that the human beings of today are exactly the same as the human beings of five thousand years ago. But our technology today is vastly superior to early human civilizations.
I understand your point, as the only difference between a human now and 5000 yrs ago, is physical feature. Our brains take much much longer to evolve. However, what you fail to consider is that if this race has superior techonolgy, in order to maintain and use this tech it must be first understood. If you give a child instructions to build a particle accelerator, you think they would be able to do it? I think not. Same goes with this superior tech, you must have a better understanding of the universe and how it works in order to use it. Certainly any species who can build an engine which can go faster than light, obviously has a better grasp on the universe, than our top scientists, who are still struggling with einstein's theory(and how it is possible to travel faster than light, if possible) as well as trying to bring about an unified theory. Superiority means to me what i said above, a better grasp on the inner workings of the universe. Therefore, any aliens which can travel to earth will be superior
intellectualy. However, the rest, i.e. culture, language, etc. is all relative. So, if youre theory is correct, if we bring back a person from 5000 years ago and raise them on out society, would they be as capable as anyone now? Yes i certainly think so.
Damn star trek-ish TV shows and movies brainwashing people into thinking that superior technology=superior intelligence.
Frankly, Im insulted that you would say such a thing!

. me, brainwashed, nah......[drooling]must watch star-trek....[/drooling]