Actually... if all animals were "equally" intelligent I would say you have a good point. The problem it, they aren't. Cetaceans,Corvids, Hominids are all pretty darn smart. So the real question is "why is there a wide variety in intelligence in animals to begin with?"
The fact we are at the top, well that is good for us. Now why aren't there any others equally intelligent. Well look at our known history. The farther you go back in time, what do you see? Simpler and simpler intelligence in man, right? Go back lets say, 6000 years what do you find? The dawn of civilization. Now keep on going.... you find evidence of some culture... but all those things you mention aren't around yet... so why is it it just happened "recently"?? (and no... it isn't young earth theory being right, radioisotope dating blows that away).
So mankind is simpler...and simpler...and simpler the farther in time we go back... and... if he is anything like some of the primitive cultures that existed until recently, he doesn't have any of those traits you mention or at least, isn't exhibiting them in a complex fashion, right?.
So what does that suggest to you? I mean... if we take it to its logical conclusion the farther you go back in time, the simpler mankind was?
Now your question about why other animals do not exhibit intelligence like man does, you have to remember we are living in a small frame of time compared to the overall history of Earth. If predictions are correct, our sun has another 5 billion years to go. That is a heck of a lot of time between now and then. If you believe in microevolution... then is it hard to believe that over a long period of time the sum of the changes in a species would enable them to gain intelligence such as we posess? Many hominids seem to be close to having that capacity right? Cetaceans are also pretty darn smart. It isn't a stretch of the imagination to see that could happen. Am I saying it will? Nope... I am simply saying it is all possible.
"...Cetaceans,Corvids, Hominids are all pretty darn smart...."
How is intelligence formed?
Is it commonly thought then that all mammals (pigs, horses, whatever) were simpler in intelligence thousands of years ago than today? In other words, our modern day sheep are much more intelligent than they were a few thousand years ago? Every animal is evolving smarter in their intellect? 30,000 years ago did we have a bunch of dumb animals? And 30,000 years from now, if they're still around, sheep will be much more intelligent?