I always thought that by the time of A New Hope the Empire was using conscripted armed forces ( In the ANH radio drama Luke was applying to the Imperial Academy) , and that the use of Clones ended back in the days of the clone wars, I doubt they could constantly churn out Jango clones forever, and the clones from AOTC would only have a limited shelf life, what happens to Clones when they are too old to fight? Old Clones Home? and surely all the Imperial officers in the original trilogy rose up through the ranks of Troops and none of them look like Jango Fett.
I think this will probably be explained in episode 3