“Will you place on it such creation as will cause disorder therein and shed blood! - But we strive to manifest Your Glory (in the Universe)!” He answered, “Surely, I know what you do not know.”
Probably the angels had seen man creating trouble somewhere else and wanted to keep them away from the earth. Angels are not supposed to have prior knowledge of anything except what Allah tells them.
Another example or proof that man was not created from one man and woman is that they speak different languages. Off springs of one Adam and Eve should speak the language of their parents.