Human cloning is unethical because humans are more complex than animals. They have feelings that need to be addressed when making a copy. Animals have a simpler version of emotion, but humans can form relationships and communicate feelings through words eventually. There is too much room for error when cloning humans and the ramifications are too much.
Human cloning is unethical in part because there is no assurance that the process safely can be undertaken. Scientists cannot come close to guaranteeing that the result of a human cloning process would be a physically and mentally stable human being. In addition, the process of cloning a human is unethical because of the potential for it being turned into a system for harvesting organs and other body parts.
Creating human clones likely has applications in creating human-like drones or foot soldiers. Creating human beings for these purposes without them being able to exercise free will over their lives seems immoral in a country which is based on beliefs that every person should have the freedom to choose how to live his or her life.
No, cloning humans in and of itself is not unethical. Creating incomplete beings for the purpose of harvesting organs would be unethical, but cloning individuals gives scientists a chance to strengthen proportions of the population with dominant genes that contain healthy conditions. Cloning could help eliminate the problems that recessive genes can create, such as hemophilia.