there isn’t a single serious project written exclusively or mostly by an LLM? There isn’t a single library or remotely original application

IMHO "original" here is the key. Finding yet another clone of a Web framework ported from one language to another in order to push online a basic CMS slightly faster, I can imagine this. In fact I even bet that LLM, because they manipulate words in languages and that code can be safely (even thought not cheaply) tested within containers, could be an interesting solution for that.

... but that is NOT really creating value for anyone, unless that person is technically very savvy and thus able to leverage why a framework in a language over another creates new opportunities (say safety, performances, etc). So... for somebody who is not that savvy, "just" relying on the numerous existing already existing open-source providing exactly the value they expect, there is no incentive to re-invent.

For anything that is genuinely original, i.e something that is not a port to another architecture, a translation to another language, a slight optimization, but rather something that need just a bit of reasoning and evaluating against the value created, I'm very skeptical, even less so while pouring less resources EVEN with a radical drop in costs.