Whereas myself... I know people in general can have a variety of responses to any given stimuli. But I know exactly what response I will have to a stimuli that has just occurred. From my point of view, I am very free-willed! After all, I'm "choosing" one out of a multitude of possible responses to this stimuli. But really, my "choice" is determined by physics, and the illusion of free will is exactly that I -- as the sole entity with the capability to observe my own internal state -- can predict my response, and no-one else can.
I think also, an additional factor is that of volition: the actions I take should somehow derive from, and act to fulfill, what I consider to be my (chemically deterministically determined) desires. Otherwise I might perceive "someone else" to be in control of my person.
But, if we were to speed your brain up a million times, when you look at my brain, it might seem a lot more predictable - much more like an inert machine than a dynamic animal. So there's a kind of relativism to whether one subject perceives another subject as "alive" or free-willed, given their own context.