Actually we do, the cerebellum is what the neural networks in LLMs were partially based off. It's essentially a huge collection of input/output modules that the other parts of the brain are wired into which preforms various computations. It also handles motor control for the body and figures out how to do this through reinforcement learning. (The way the reinforcement learning works is different to LLMs though because it's a biological process) So when you throw a ball, for example, various modules in the cerebellum take in inputs from the visual centers, arm muscles, etc and compute the outputs needed to produce the throwing motion to reach your target.
We also have the cerebrum though, which along with the rest of the brain is the magic voodoo that creates our consciousness and self awareness and we can't recreate with a computer.