I brought this up before to a teacher (who was Christian) when we were talking about religions of the world. He had no idea how to answer this question
If Adam and Eve have belly buttons that would mean they would have had to be born not just put on the earth, and if god made Adam and Eve of his own image, that would mean god would have a belly button, and if god has a belly button that would mean god would have had to have been born by someone lol