I think your problem is that you see everything within time as linear and so your lack of comprehension forces you to place a god at the beginning of this long line. It is the same reason primitive societies made gods for rain, sun, wind and so on. They did this because they did not have the scientific means to understand these things. Slowly over time, all these gods, through through the power of kings and rulers who wanted to maintain fear in their subjects, shifted all these gods into one single god with themselves as "his" representatives on earth.

If you want to comprehend evolution, you have to except two notions. One is that human beings are incable of comprehending infinity and secondly that time and space cannot be looked at in a flat and linear manner. The root of earth evolution is in the fact that for an infinite amount of time throughout space energy has continuously been transferred through various celestial phenomena. One phenomena would create another and another and another and so forth.

Do you ever ask yourself how mold grows on old food? It came out of nowhere didn't it? Well, not really, the obvious observation is that certain combinations of elements cause these things to occur.