Why doesn't TOG year 1 start with studying creation?

Because the curriculum is written in the supposed order that Moses wrote the Pentateuch. Some scholars believe that he wrote the story of the exodus first.

There is a section in y1 u1 that explains this, and there are suggestions on how to adapt the curriculum to start with creation (week 4) and progress chronologically.

HTH

Well it's also because Moses wrote the first books of the Bible so we start with his back ground. The idea that he wrote Exodus first is not in anything you teach.

However you can be pretty sure that he grew up in Egypt, left, had an encounter with a burning bush and then wrote all five. So they simply start with his life and then when you go back to the creation story and Genesis you can pull out things someone raised in Egypt (which was also his audience) would have seen that we don't see.

You can rearrange the weeks to reflect a more chronological history.