” . . .starting with simple single celled organisms . . ..”
There is nothing “simple” about the protoplasmic substance of an amoeba. It is biochemically complex well nigh beyond human comprehension.
Which leads to the question, from whence the phenomenon we call “life?” Creationists say God created, and proceed to study what He created, trying to explain and understand whatever can be known about them, classify living entities, etc., etc.. Evolutionists likewise, but for their lack of an answer to the initial question.
Okay. You're no more complex than an amoeba. Happy?