> People have been thinking about why the brain thinks for a very long time and so far we have absolutely no idea
I'm not sure what you mean by this.
I think there is a pretty large consensus that our neocortex is a prediction machine (predicting future observations/outcomes from past experience), and the reason WHY it would have evolved to be this is because there is obvious massive survival benefit in successfully predicting how predators and prey will react ahead of time, what will be the outcome of your own actions, etc, etc. Prediction unlocks you from being stuck in the present having to react to things as they happen and lets you plan ahead.
Thinking = Reasoning/Planning is just multi-step prediction.
I don't think consciousness is the big deal most people think it is - it seems to be just the ability to self-observe (which helps to self-predict), but if we somehow built AGI that wasn't conscious, then who cares?