I would describe PIAAC literacy levels 1 and 2 as barely able to comprehend English, and someone who wrote at a corresponding level as barely able to write. They're close to the line of illiteracy, particularly PIAAC 1.

I believe the median person who comprehends English to PIAAC level 3 literacy or above, and writes accordingly, would be more comprehensible than an LLM, if we controlled for correctness and for their own understanding of the subject matter.