And, yes, Adam did will himself against God. Was Adam "free" not to fall? Well considering that God planted the tree in the garden and knew what the outcome would be, what do you think?
God gave man one commandment. Man, in his perfection, couldn't even keep one commandment with all of paradise at his feet. That is the whole point of the tree.
Let us not forget the angels. They had free will and 1/3 of them rebelled and were swept from the sky. Like Adam, the angels were made sinless, yet not divine. A lot of folks get the two mixed up. Foreknowledge is not predestination.
Where on earth does it say the angels have "free will"? Honestly, people need to read the text and only the text. The angels clearly have a will. That will is bound as our will, to either do the things that are of God or not. They are slave to righteousness or slaves to sin. It is not "free" to make choices. Otherwise we be seeing angels falling out of the sky daily.