If I were in your shoes, I'd start looking at the possibility that James is the son of John, son of Boston Shew. Here's how I come to that possibility.
First: 1860 Cherokee County AL census, John Shews and wife Mary H. Shews are shown on page 106 with son James L., age 3, and daughter Frances E., age seven months. I believe this John Shews is the John Shew shown on the 1850 census with Boston and Elizabeth Brewer Shew in Cherokee County even though the age doesn't match up well. The key facts are that this 1860 John was born in North Carolina and that he's on the census immediately following the family of Lewis and Mary Shew Day. Mary, John's wife, is shown as 23, born AL.
Second: 1880 Marion County AR census, James Shoe, age 21, and Eliza Shoe, age 18, both born AL, are shown as stepchildren in the household of Barry (Crubs?), age 52, whose wife is shown as Mary, age 42, born AL. That's a three-way match to Mary, James L. and Frances E. from the 1860 census, with the single discrepancy as to how old people were (and that's a common error).
Third: James is shown as James L. Shew on the 1900 and 1910 censuses in Marion County, always born in AL, always around 1857.
Seems to me you have a fairly compelling case. But James Shew lived beyond 1930 -- he was still alive as of the 1930 census -- so you should be able to get a death certificate and see what that says, and possibly get an obituary as well. Plus he seems to have had a TON of kids, including one born to a second (or later!) wife around 1915, so I wouldn't be surprised if he doesn't have living grandchildren still in the area.
One of these days you and I are going to have to trade gedcom files... I'm descended from Boston and Daniel through Daniel's daughter, Gilford's sister, Martha Louise.