The author of the opinion-page column "Someone Democrats Are Overlooking," July 30, is not the only one who is hoping for a big future for Jimmy Carter. His greatest and strongest attribute is his interest in human rights as a primary motive in human relations. The choice of a United Nations secretary-general is coming up sooner than the next US presidential election, and I hope he is chosen for that post.Carter's achievements in Camp David surely indicate his abilities to the world and the current 1980 hostage-release questions will tell people that he would have been reelected if all the facts had been known then. Inga Thompson, Minneapolis Letters are welcome. Only a selection can be published, subject to condensation, and none acknowledged. Please address them to "Readers Write," One Norway St., Boston, MA 02115.