Has any experiment ever refuted the following reasoning:

(1) - Single celled organisms do not have free will. They just move towards/away from nutrient/pH/salt/etc gradients sensed by receptors in mechanical ways. Tiny machines. Like atoms in a chemical reaction, but bigger.
>No free will
(2) - Microscopic multi-cellular organisms are just bunches of single celled specialized organisms doing the same. From (1), since none of the constituent parts has free will, multi-cell organisms also don't have it.
>No free will
(3) - More complex animals (nematodes, arthropods, etc) have bunches of single and multi-cell specialized organs and tissues, each of which being constituted by (1) or (2), and as such, no free will.
>No free will
(4) - OMG HUMANS ARE DIFFERENT OK WE TOTALLY HAVE FREE WILL BECAUSE I'M SCARED OF THE IDEA WE DON'T I MEAN I AM DECIDING THINGS RIGHT MY BRAIN DOESN'T ACT ALONE RIGHT PLEASE MOMMY PLEASE