I like this idea.
At the least, I think it does a good job of calling attention to other bits of human history that existed before people started writing things down. People had to learn how to farm, build, and do many other things in order to even justify starting building houses – let alone entire communities. Humanity has gone quite far in a short amount of time.
One drawback, though, is that it doesn’t fully encompass other parts of human prehistory. Ancient lunar calendars sometimes date back to the Paleolithic Period. Even before people started modifying the world around them, they did learn that the world had at least some sort of natural order to it.
I will say that having a different calendar is a good thing, if only to get people thinking about the achievements of cultures before theirs. None of us would have the life we live without the many generations prior who decided to change their world for the better instead of following food around. We are more connected to the thoughts and actions of others than I am comfortable admitting at times.