Rule #2: The human brain evolved (we have three brains)
We don't have one brain in our heads; we have three. We started with a "lizard brain" to keep us breathing, then added a brain like a cat's, and then topped those with the thin layer of Jell-O known as the cortex--the third, and powerful, "human" brain.
We took over the Earth by adapting to change itself, after we were forced from the trees to the savannah when climate swings disrupted our food supply.
Going from four legs to two to walk on the savannah freed up energy to develop a complex brain.
Symbolic reasoning is a uniquely human talent. It may have arisen from our need to understand one another's intensions and motivations, allowing us to coordinate within a group.