Every person ever conceived has some role to play in God's creation. As members of the body of Christ, we, more than anyone else, whether Jew or Gentile, have a divine commission to act in some unique capacity as a functioning organ in that body. Nobody is without purpose, without a role to play.
Just as in a physical human body, no two parts are identical. The right hand is not the left. A foot is not an ear. A skin cell is not a neuron. If any one of these tries to play the part of some other, it cripples the body to some degree.
A hand can perform the function of a foot if necessary, but it will never be a good foot. The body functions best when every part plays its own role and doesn't compete with any other part.