When a pre-schooler touches something hot, he learns that it burns. If he climbs on a chair or up the stairs, he learns that he can fall down.
Most children do fall and bump their little head.
In child development, the child progressively learns by natural instinct how to use logic to ensure that the basic needs of life are met. The pre-schooler even learns to be safety minded by not trying to chase and catch bees. It should be the other way around, the bee chasing him. True maturity does not only consist of going through the phases of child development, getting a job and finally settling down with a family. That is worldly maturity.