Humans have free will on the basis of not having obtained immortality (
1 Cor 15), not having eaten from the tree of life and sealed our destiny yet (
Genesis 3). We have been made a little lower than the angels. (
Ps 8:2-7)
Angels, having been created immortal, have no recourse for sin.
(
Rev 12:7-12) (
Rev 20:15)