Your child is developmentally appropriate.
This is normal.
Be glad.
Comprehension/understanding comes later.
He is only 2.5 years old. Things occur in developmental stages, not all at once.
Some start sooner, some later.
Bear in mind also, that their emotions and understanding and communication of abstract concepts, are NOT even fully developed yet.
He is not fully developed yet.
The brain is not even fully developed yet until 26 years old.
A kid this age does not even know FULLY about opposites or "rules" nor do they have full cognition of everyday life or reactions nor about deductive and inductive reasoning.
Even Kindergarten aged kids, go through this.