Where Did the Amoeba Come From?

This is a chance for the evolution science world to give an explanation to where we came from. Let's go back to the amoeba. According to evolution, animal life started out as an amoeba right? Well, in that case, please explain the process by which the amoeba came into existence. Also did all life come from that amoeba including plant life, or did plant life originate another way? If plant life is separate from animal life how did it originate?