Early generative AI at least had the virtue of relentless, unsettling weirdness, in the same way that generative art from the late 90s and early 2000s did. A handful of people made creative use of that spooky weirdness.
Now it turns out "Airspace" art.
If you took the best, most creative, human writer in the world, and for thought experiment reasons they had amnesia (to mimic AI blank context windows) specifically while you asked them for a story idea 100 times in a row, my expectation is that this human would also give you the same idea at least 80 times out of that 100.
* still better than the mean human, but even the top 0.1% of humans aren't all professional authors.
What you think is better is not what I think is better. Imagination is not storytelling. You ask the "mean human" to write, it's going to be worse than an LLM in spelling and grammar, if you get anything at all.
Most humans never do a creative writing course after school, and the longest fiction most people will write is their resume description of what their previous jobs involved, or perhaps their dating profile.
Don't mistake what you see published (or what your friends are like) for the average human: the average Hacker News comment easily above the writing grade (and creativity) of e.g. many of the one-shots stories I've seen attempted on some creative writing subreddits. "Mean" is not a high bar.