If you now look at the parts of the brain where exceptional things are developing, you will see that these are completely different parts than those after birth. That in itself demonstrates how much baby has already developed in their first half year of life.
The parts of the brain that play a role in cognition and learning, language, and social emotional perception are highly active at this time. That does not mean, however, that the other parts of the brain are not active. The brain is always active. If you study the leaps that your baby is going through during this period (relationships, categories and succession), you will see that they are all related to the parts of the brain that are undergoing the greatest development at this time.