The human brain is a very fast tool that helped humans survive for thousands of years. The brain controls movements like typing, and it has to be very precise movements. It also manages speaking, recognizing other peoples and places, and understanding location and direction.
If you think about a human like a computer, with hardware (body) and software (mind) then the hardware does not change much while the software changes every day for humans. The brain is able to process thousand of different things at once and not drain all of your energy.
Computer are capable of doing lots of processes all at once which makes it an interesting comparison. With the ability that Artificial Intelligence has the internet can learn new things on its own. The brain is not built specifically for understanding one thing, it is better for understanding a large amount of things, and processing them all at the same time without the person getting overloaded with information.
Typing is insanely accurate (if you can type good) and each movement require your brain to do a calculation to know where to place the finger, how much pressure to use, wait for a reply from the key (pressing it down) and then telling that finger to let go of the pressure to let the key back up. Then it has to move the finger to the next spot and do that all again. For person like me, this happens ten of thousands of times per day.