One rational argument maintains that a genuine originator knows the relevant details of what it originates. Since human agents do not know every minute detail of their actions, this is offered as evidence against describing them as independent creators.
Walking looks simple, yet it involves varied limb movements, different speeds, pauses, and intricate coordination. A person intends to walk but does not consciously represent every component of the process in detail.
The argument does not equate lacking detailed awareness with lacking all choice. Someone can intentionally perform an action without possessing exhaustive knowledge of the physical processes accompanying it. The claim under examination concerns independent origination, not whether the person can be said to act.