Let me elaborate, how likely is that there’s an animal on earth that’s smarter than us? By smarter, I understand intelligence is a nuanced topic unique to different animals, so for the sake of argument, let’s talk about, mathematics, critical thinking about where and how to apply those mathematical concepts, and creativity in any form.
There may be some mental tasks that other animals can probably do better than humans. However, if you’re talking about complex topics like mathematics, I would bet on modern humans being better given that being good at math is far more likely to be an evolutionary advantage to humans over other animals.