Behavior/dynamics depends on structure, and structure is scale dependent.
At the scale of galaxies and stars, the universe has a relatively simple structure, with relatively boring dynamics mostly governed by gravity and nuclear fusion.
When you zoom down to the level of dynamics on a planet full of life, or of a living entity such as a human, then things get a lot more interesting since at those scales there is far more structure causing a much greater variety of dynamics.
It's the structure of an LLM vs the structure of a human brain that makes the difference.