There are some similarities between Matt and Attean's relationship and Friday and Crusoe relationship.  One of them was saved in each story.  Matt was saved by Saknis and Friday got saved by Crusoe.  They both came close to dying.
      In both stories a white man and Indian were friends.  Attean and Matt were good friends.  They became friends when Sanknis saved Matt from drowning.  Crusoe and Friday became friends when Crusoe and Friday from savages.
       Another similarity is that both white men were alone with nobody coming for him, but Crusoe's bout crashed and was alone until he met Friday.
        Those are the similarities.