I find the discussion on the Libet experiment troublingly unsophisticated.
No-one would deny that when I wave my hand that an impulse has been directed along nerves; and that this transmission physically happens just before my hand moves; (and of course it happens before as it must do, and not after) though of course I think it happens just when I think of doing so - there is an illusion of simultaneity.
But there are two unlike things being compared here: myself to myself, and myself as a physical object. These are qualitatively different.
Supposing that there is an exact Correspondance between mental acts and physical acts, at every level; then this, by itself does not deny free-will.
But of course it's not by itself, and this is where the crux of the problem lies: in that physical acts are seen as determined; and this is prominently a conception of the mechanistic philosophy as derived from Newton.
But consider that the first mechanistic philosophy (in the West) was originated by Democritus; and elaborated by Epicurus and put down in well-rounded Latin hexameters by Lucretious.
And that in this conception we see that atoms are in a sense given free-will (the Clinamen) so that they will interact; this, had any one bothered to note it with sufficient acuity at the time will have brought out the notion of uncertainty in physical motion as an irreducible notion before the advent of QM.
What I'm pointing out here is that, in Antiquity, taking the notion of the will seriously brought out a physical notion; whereas we seem to be troubled now with taking determinism seriously as seeing all our acts as determined.
Schopenhauer took the Will seriously enough that his philosophy was wholly based on it.