There are A lot of intelligent species on earth actually. The question is in how you define "Sapient" because frankly the word is supposed to imply some relation to humans. However if you mean simply in terms of concious or self aware species yeah there's a few. Gorilla's are a well known example, and some notable individuals like Koko the gorilla have learned sign language and can hold conversations with humans through sign language and understand many of the same concepts we do.
Dolphins and Whales are known to have a language of their own we just don't really understand it yet.
Most social animals are almost certainly intelligent we just don't know how to communicate with them.
To put it another way it's like the difference between "I don't understand" and "I understood but I don't care." Even if a cat or dog understands what you're saying to it understanding is not the same as obedience. Just because something understands you doesn't mean it's just gonna go "oh ok lemme do what the human says." that's one of the many arrogances we have a humans in searching for intelligence in other species we seem to assume things don't understand just because they don't do what we tell them to do.....even though we know everyday animals like cats and dogs are intelligent enough to recognize many words their inability to adequately communicate or express their own intents leaves us bewildering when they disobey or do something else entirely.
Objectively any social animal is probably intelligent because some degree of intelligence is a requirement for communication as you can't convey or understand concepts without it. The only question really is what level of complexity can their intelligence extend to.