I am not so sure there are any meaningful limitations on its capabilities. We can build machines that far outstrip our physical abilities with relative ease, I see no reason why we cannot do the same with our brains.
The limitations may well be not in our brains but in the object of our investigations. The planet itself may not support the kind of physical and mental activity required to make all those technological leaps. For every Mars lander there are about a hundred million Nike tennis shoes. For every cyclotron experiment there are about a hundred million mindless tweets. For every Einstein there is a Hiroshima.
While our intellectual capacity does not seem to me to have any meaningful limits, I think our emotional capacity is equally limitless as well. We seem not only to be able to conceptualize what others may think or feel, we can create fictional characters as experiments to conceptualize what could be possibly be thought or felt just to see what will happen and share in those emotional highs and lows. It's what religion, otherwise known as fiction, is designed to do. For every god there is a Satan. For every heaven there is a hell. For every St. Stephen there is a Torquemada.
It seems we have become so adept at the development of systems to expand our abilities we have forgotten how to simply be who we are right here right now. It seems that there are people who don't know, or care, where their food comes from. There are others who are so enamored with ideological constructs they are willing to kill for a fiction.
I wonder if the human race is finally beginning to reach a point where the planet and our own bodies can no longer support the unlimited ability of our brains to seek out novelty both without and within ourselves. The solution to that problem, if it exists, may be the most important solution the human race has found since we walked out of Africa.