How else could information be compressed in human brain besides a similar statistical graph nature and networks of relationships being created representing various different patterns and models of the World.

In some other way which we don't know about.

Just because someone can't imagine the universe to be structured in any other way than being built from microscopic Platonic solids, tightly packed and touching each other and filling all of the universe without gaps or empty space, doesn't mean that this is how the world actually operates.

If you don't know, how do you know that this is not it, and that the understanding is different and that an LLM doesn't understand and we somehow do?

According to this logic there are also intelligent aliens living beside us.