That is not true, jambo, Mother Nature tried many different paths to intelligence. Many animals besides humans are highly intelligent, e.g. dolphins. They have a well developed language (I think they can produce up to 100 sounds). Unfortunately they took to water, where there is no need for intelligence. It was a dead end as far as nature was concerned.
Another path to intelligence was the elephants. Elephants are highly intelligent; they have excellent memory and can pass knowledge from generation to generation. Scientists have found instances of the Matriarch of the herd leading the herd to a water source in the time of famine, one which she has never seen before.
They have also observed elephants mounting fake raids. Two or three elephants would raid a farm, drawing the villagers after them, while the main herd invades a totally different farm.
Scientists also suspect that elephants perform some kind of ritual when they come across the bones of other elephants from the herd. They sniff at the bones, they circle around it, they walk around it.
Elephants also have a highly complex social structure. Elephants show most of the signs of intelligence, if on a smaller scale. African elephants have two fingerlike protrusions at the tip of their trunk (Asian elephants have only one).
It is not to hard to imagine elephants developing more of such protrusions, giving them fingers to work with. That would give them the ability to make tools. I personally think that three was a competition between elephants and hominids as to who develops intelligence first, and hominids won by a hair (a few million years). If humans had not developed intelligence for a few million years, it is not inconceivable that the world would be populated by intelligent elephants today. But once humans developed intelligence, it put a stop to any further evolution.
I don’t think there is anything unique about intelligence. Mother Nature tried many different paths towards intelligence, and one of them (hominids) succeeded. Another (elephants) could equally well have succeeded.