A Map of the Commonwealth, ref. 1

       What I was seeking was human society -- any society except that of
    Golias', that is -- but when I did find a footprint in a patch of moist
    sand, it scared me.  The print was a huge one, much too big to be made
    by the man I was sulkily dodging.  If the foot had been shod, I would
    not have been alarmed; but it wasn't.

Making their way to a new island they separate and each engage in a bit of exploration, yielding some food and water and a bare footprint that gives Silverlock a bit of a turn. Normally signs of a bare foot on a sandy island beach wouldn't be cause for alarm, especially for Silverlock given that his last encounter with a properly shod island-dweller left him a hog.

Leading with a little caution this time proves entirely appropriate, in that this is clearly Robinson Crusoe's island. Crusoe's story has a major turning point shortly after the scene where, noticing a bare human footprint after years of solitude, essentially he has the same response as Silverlock.

Myths and legends about travel in remote lands often feature cannibals. Anthropophagi and the like have been a hazard to fictional sea-farers for a long time -- thousands of years lie between Odyseus' Laestrygonian adventure and Othello's brief account. The mere fact that Silverlock has stumbled upon a cannibal bed-and-breakfast doesn't restrict us to any particular work of literature necessarily. Unique identification depends on the footprint scene and the ceremony they witnessed thereafter. Making off with a canoe is arguably at best a glancing reference.