LLM'S don't work like the human brain, you are comparing apples to suspension bridges.
The human brain works by the series of interconnected nodes and complex chemical interactions, LLM's work on multi-dimensional search spaces, their brains exist in 15 billion spatial dimensions. Yours doesn't, you can't compare the two and come up with any kind of meaningful comparison. All you can do is challenge it against human level tasks and see how it stacks up. You can't estimate it from complexity.