"The software is the sum total of collective human culture they are trained on."

Almost, they are the median or most popular aspects of the culture upon which they are trained. So you are getting the most popular way to do something, not the best (for some definition of best). That's why the claims about LLMs being geniuses is absurd. They almost by definition are going to have the average IQ of all the people on the net weighted by how much each person posts. I'm guessing that's about 95.