Samuel Johnson called it the vanity of human wishes, and Buddhists talk about the endless cycle of desire. Social psychologists say we get trapped on a hedonic treadmill. What they all mean is that we wish, plan and work for things that we think will make us happy, but when we finally get them, we aren't nearly as happy as we thought we'd be.
When nobody read, dyslexia wasn't a problem. When most people had to hunt, a minor genetic variation in your ability to focus attention was hardly a problem, and may even have been an advantage. When most people have to make it through high school, the same variation can become a genuinely life-altering disease.
If you just casually look at a baby, it doesn't look like there's very much going on there, but they know more and learn more than we would ever have thought. Every single minute is incredibly full of thought and novelty. It's easy as adults to take for granted everything it took to arrive at the state where we are.