Buddha always spoke what accords with common sense. Common sense is that human language develops constantly, words are constantly being invented by human beings. For example all the words connected with Computers, they have come up very recently, they have been made up and invented by human intelligence.
The Bhagavan may have invented some words himself, he gave existing words a new specific meaning that he himself explained and defined. For example the words "brahman", "aryan", etc...
The ability to communicate is inherent in a living being, even the animals have different means of communication, like the ants and other insects. They have a sense of orientation, sense of paths, sense of different places, and logically also a mental map in their minds, how else could they function in a world of concrete form and objects? And an ability to communicate this information.
Language develops gradually because communication is inherent in the nature of living beings.
Interesting thing is that Vimalakirti sutra and Lankavatara sutra say that there other worlds where beings communicate through different means than the spoken language of human beings. The list of means of communcation is longer in the Lankavatara, it includes communication through scent, through coughing, through telepathy, etc... In Vimalakirti there is the Feast Brought by Emanated Incarnation where dharma is communicated through taste, through this special kind of food.