Correct. The Clone Troopers were clones, which in the prequel movies is very clearly pointed out, but by the time of Episode IV: A New Hope the Empire had been recruiting from the general population. Much like most wars which drag on for a while, the elite forces end up having to let in new recruits to fill in gaps from those who were lost. These recruits might not have more than just some basic training, and when rebels then infiltrate weapons manufacturing plants and fiddle with the quality of the guns provided to these troops (IIRC mentioned in Andor if not elsewhere), it's no wonder the Storm Troopers had worse aim than the Clone Troopers.