"What example, artifactual, experimental or theoretical, do you have of a one-celled organism that is more simple than the simplest known one-celled organism? Without one your refutation is empty."
Because we have had 3.6-3.8 billion years of evolution. Evolutionary processes have touched all organisms, including single celled ones. Basically our Ichneumonoid friend is telling you that just because there is no 3.8 billion year old microbe in existence today and I can't show it to you under my microscope, doesn't mean that there never was one.
So you believe, on faith, that there must have been a simpler one-celled organism than exists today? You have no proof in any form. I don't believe things on faith.