The people in Robinson Crusoe

Why do all the people Robinson comes across ( such as the portuguese captain, the english captain and even the pirate that enslaves him) appear to be good people and behave in a goodly manner? They all seem to be too willingful to help him overcome whatever obstacle he currently has in his way without expecting anything in return. Even his master the pirate is a kind master that does not mistreat his servant slaves. Which is clearly abnormal in a world where apparently evil exists ( Robinson mentions the Devil himself too). Why is it so in this book?