George W. Harriman 1821

I am looking for the ancestors of George W. Harriman born 1821 Washington Co., PA.The name was originally spelled Haarryman. He married Jane Turney, Eliza Jane Johnston and Lucinda Ellen Keller. I show the line as follows but am not sure this is correct:
John b. 1671
Robert b. 1711 MD
David b. 1756 MD
Samuel b. 1795 PA
George b. 1821PA
Mary Ellen b. 1857 OH
Hopefully, someone can let me know if this is correct or if I am way off and when the family immigrated. My line comes from Mary Ellen Harriman Ruckle.
Thanks for any help.