Why does Islam restrict the theories of the origin of existence in the inevitability of the existence of one valid truth?

The existence of diverse theories and convictions among mankind does not negate the fact that there is only one valid truth. For example, regardless of the number of concepts and notions that people may have about the transportation means someone uses who owns a black car, this does not negate the fact that he owns a black car. Even if the whole world believes that this person's car is red, such a belief does not make it red. There is only one truth here and that is: the car is black.