We use existing languages not because we love to copy, it's because languages are a medium for communication. They're only useful if they're understood by others.
If you wanted to prove a point: writing is much, much harder to invent, yet it was invented independently at least 3 times in history. By definition LLMs can't invent something truly novel like writing. Because nobody trained the first writers. There was no "training set".
It's fine, LLMs can still be useful. Science is looking at the gaps and most of the gaps that are useful are small and LLMs can explore those faster than us. That could potentially improve many lives. Though not in this corporate LLM world, most likely.