Which German-born trapper and frontiersman was said to be the inspiration for Natty Bumpo, the main character in James Fenimore Cooper's "Leatherstocking Tales"?

A trip to Hoosick Falls in Rensselaer County, NY, wouldn't be complete without a drive down Main Street. As you pass the cemetery, with row upon row of stone monuments dissected by shade trees, an interesting red and gold marker catches your eye. The title reads "Natty Bumppo" a name that is familiar but you can't quite place it just yet. Reading the marker's text, those hazy details come streaming back:

NATTY BUMPPO
IN THIS BURIAL GROUND LIES
NATHANIEL SHIPMAN
THE INSPIRATION FOR JAMES
FENIMORE COOPER'S FAMOUS
"NATTY BUMPPO" CHARACTER

So according to the marker, this is where Cooper's inspiration came from, a man named Nathaniel Shipman who lies buried in Hoosick Falls.

But, if you drive about 100 miles to the west to Fly Creek, near Cooperstown, NY, there is another red and gold sign with the same title, but the story is different. This one reads:

"NATTY BUMPPO"
DAVID SHIPMAN, CA. 1729-1813
BURIAL SITE OF LOCAL HUNTER
KNOWN BY & INSPIRATION FOR
JAMES FENIMORE COOPER'S
LITERARY CHARACTER

So what's the story here? Was David Shipman the true inspiration or was it Nathaniel Shipman? What was their connection to James Fenimore Cooper and what led to a war of words in 1874 which threatened a lawsuit over erecting a monument?