Quite a while back, I compiled a family history on the Astle family with all the various branches that I could find in the area early on.The elder James Astle on the 1784 list is my James, based on the makeup of his family.Angelica was born in 1774, Hannah about 1776, John in 1779 and Daniel, my line, about 1783.If your James was his son, then it was by a first, unknown marriage, which is certainly possible,since we've never been able to find out anything about him before his Nov 1770 marriage to Elizabeth McLane in Schenectady. I also have no proof of a year of birth and 1740 is only a wild, but reasonable guess.
I don't know if your James was a son, or a cousin or nephew.However, the name is unknown in colonial America except for one Ensign Daniel Astle with the Black Watch in the French and Indian War in the 1760's (based in Albany).The two lines liked many of the same given names, including Alfred, Daniel, James, Thomas, William and John for the males, along with Sarah,Jane and Angelique/Angelica for the females. There is also an Angelica born in Derby, England about 1770, as I remember from the IGI.There are tons of Astles there.However, the Black Watch was based out of Scotland.
Also on the refugee ship with James Sr. was Robert Flowers, likely the father of Sarah.
I'd love to find out more about these earliest people, but records don't seem to exist.