It makes for an interesting story, although I don't believe all of it. Nunez was writing his report to the king of Spain and naturally attempted to make himself look good. He also wasn't much of a writer by modern standards — it's often difficult to know just who he's referring to. But under the circumstances, that's not hard to understand. He and the other three men must have been very resilient, although their inability to find food or clothing or anything else connected with civilization leads me to think they weren't very resourceful.