I must disagree with the above. The American Colonists were very literate. The US was perhaps the most literate country in the world at the time of the revolution. In a country of just a few million Paine's booklet sold hundreds of thousands of copies. Your other point may be true also however. The stamp tax also taxed legal documents of which all had a need for.
The first wave of immigrants (1600s) were quite literate, being made up of middle and upper class families but succeeding waves were not.
The primary instruction was in the home, this being an important part of a motter's duties and the child was put into a private school later, frequently a school directly funded and maintained by a church.
One source states that only 4 of 1000 colonialists were iliterate, a rate of literacy that is far higher than we have today.
Thanks for the correction.