The Ur-language

When the Light Bringer cracked through the Void’s shell and brought life to the worlds, He recognized the need for this life to communicate with one another. 
The life of these worlds was new, newer than anything He had encountered before. In the blinks of an eye, worlds formed and died. Species of plant and animal stepped onto new worlds only to vanish as if they had never existed.
The Light Bringer saw mistakes that the new life made. And He knew He could not stay on this side of the Void for much longer. He would be unable to nurture the lifeforms and prevent them from making the mistakes of their extinct brethren.
Looking out on the new creations, the Light Bringer breathed out slowly, his warm exhalation blanketing the worlds. As the gentle, cinnamon breeze swept over the worlds, what some might call a miracle happened. All life, no matter how rudimentary, gained language.
Even the rocks and waters gained the ability to speak and understand.
All life spoke the same language: the Ur-language.
The Light Bringer hoped that the new life would use the Ur-language to communicate with one another, to pass on lessons learned as they struggled to gain a foothold in the new creation.
Distance wasn’t an issue for communication. An elm tree on one planet could communicate with a mountain range on another. Stars could communicate with earthworms on planets that didn’t orbit them.
For a time, the Light Bringer’s hopes were realized. Life on the new worlds learned from one another and thrived. Eons passed on the worlds, while the Light Bringer experienced minutes. He had spent all the time He could on this side of the void, so he withdrew to the Known Planes. He believed and hoped that the new worlds would continue to communicate.
In His absence, things slowly changed as they eventually must. Some species developed sentience; others, intelligence. The intelligent species soon forgot the Ur-language. Their young remembered it and could still communicate with their surrounding. But as they matured, they knew they would forget and mourned the coming loss. Soon, though, they even forgot their grief as they forgot the Ur-language even existed.
Some among the intelligent species on Llareffe theorized about the Ur-language’s existence based on their observations of their young and of their surroundings. They withdrew from society and formed The Silent Ones with the hopes of recovering the Ur-language, while not even knowing for certain if the language existed.
In addition to the intelligent species losing the Ur-language, other pieces of the world lost the ability to communicate over great distances. Some lost the ability to communicate outside their kind. The oceans no longer spoke to mountains. Some of these losses occurred because petty spats broke out among the new life. Other losses occurred because worlds spun further apart and turned inward, not looking to the rest of creation.