YOu seem to have a common misunderstanding of the ToE. Random mutations alone don't cause evolution, it is only the power of cumulative selection of beneficial mutations over millions of years that makes evolution possible. It is the ratcheting device that allows, even demands, progression to complexity. Read any of Richard Dawkins books for the eloquent details.. . And we do say "we don't know"...but what we also say is the overwhelming burden of evidence supports this point of view, but that our minds are open for other evidence that would explain all of life in a better way. Science is open for the paradigm shift, Newtonian physics held sway for over 200 years until Einstein, and maybe some day there will be a better theory than Evolution, but "god did it" isn't the one.