Not sure if I would call Hamlet a humanist, but I can absolutely see your point. Right now I am inclined to see the possibilities of Daoism in Hamlet, just because I am reading a Chinese translation where the "To be or not to be" part is exceedingly diffcult to translate. Fact is, there is a lot of philosophy going on in Hamlet and I also think that even if Shakespeare took an old story and rewrote it, it happens to be filled with stuff he himself was worried about during this particular time in his life. Humanism might be the case - it might also be that the constant battle between religions needed him to take a course that would be met with the least resistance? Not sure, if you read Stephen Greenblatt's "Will in the World"? The ghost in Hamlet is a hint of catholic belief in a protestant time in the realm. But I totally understand the humanistic view. The influence of the antique Greek literature might have taken its cause.