The term aryan is a term used to describe a race or a population as noble and better than other races. He used it because of the indo-aryan migration theory which states that people settled Europe from the hindu parts of the world meaning that one could say that people who descend from the Indo-European languages are aryan. He used this to explain that white people from Europe are Aryans and that they are better than other races.
The reason for the expansion to the thirteen colonies was for religious freedoms as well as other freedoms. Without religion perhaps they may have neverbranched out.