Simply put: we are not the only advanced species there has ever been, nor are we the only current one. Provide any argument of our superiority over other animals, and I will provide you an example of another species that participates in that behavior.

Setting aside Neanderthals and other early hominids that were likely as smart as us:

1. Language: Prairie dogs use different alarm calls for different predator species.
2. Tool usage: Otters not only use rocks to open clams, they show preferences for more effective rocks and keep favorites.
3. Advanced construction technique: Any number of insect species would qualify, but termites in particular build structures that, by comparison, would be the same as us erecting a 4600ft tall building.
4. Sense of humor: In the book When Elephants Weep, author Jeffrey Masson recounts a story (sorry, anecdote not source - I just love this story) of a parrot that saw its owner cooking cornish hens. It cried out, "Oh no, [name of other bird that lived in the house]!" and then started laughing loudly. More scientifically (and with a source, it has been discovered that rats are ticklish, seek out tickling, tickle others, and make a noise that has been interpreted as their version of laughter.
5. Advanced social structure: I'm not even going to pick a single species for this one. Ants have assignment of responsibilities ranging from nursing to farming; groups of ants go to war and use advanced combat techniques; numerous species adopt orphans of their and other species; etc., etc.

Point being, the only activity that humans have taken part in that no other has is space travel. And that doesn't rule out advancement or sentience in other species, just that we got there first.