Believe what you want to believe, but I think that we all were created by one type of organism. From a single celled bacterium to the billions of different organisms today.
Reason#1. We have fossils that date back billions of years ago. Reason#2. I don't believe that there is a god reason#3. If you study embryology (the study of Embryos) You will see that a human and another creature's embryo are very alike
Reason #2 is not a logical argument. If I say that I believe in God, thus Creationism is real, you would laugh at me. Thus when you say you don't believe in God, thus Evolution is real, it sounds just as bad.
Anyways, here's what I say: God created the world through Evolution. THERE! Everyone wins!