Many member family trees on Ancestry.com identify the John McClain and James McClain who settled in Bath Co., Ky as sons of Charles McClain and Elizabeth Moon of North and South Carolina. I have not seen any primary sources for that attribution (e.g., none of the trees mention any wills, etc.), so I prefer to consider their parents unknown.

In 1870 he is listed with his daughter Sarah and her husband William Staton as age 77, wheel wright, born in Kentucky.

In 1880 he is listed with them as John McClane, age 88, border, wheelrite, born S.C. S.C. Vct. (I do not know how to interpret the Vct, but it is entered for several other parent birthplace fields on the page. I suspect it of being an abbreviation for unstated, in some form.)

Bath County Marriage Bonds (loose papers on LDS microfilm) contains note signed by Augustin McCarty swearing that Phebe McCarty is at least 21, and return signed by Wingate Jackson certifying that he married John McClain and Phebe McCarty on the 13th of February 1814.

1820 census of Bath Co., Ky, Owingsville, lists on p. 218:
John McCain, 3 m under 10, 1 m 16-26; 1 f under 10, 1 f 26-44.

1840 census of Bath Co., Ky, east of Slate Creek, lists on p. 226, line 20:
John McLane, 1 m 10-15, 1 m 30-39, 1 m 40-49; 1 f under 5, 1 f 5-9, 1 f 20-29, 1 f 30-39, 1 f 90-99.

The next line is Augustus McLane, 1 m 20-29 and 1 f 20-29, no children.