This might seen like too obvious of an answer, but simply put, God is working things out for His glory because He finds pleasure in it.
Sure, mankind may have derailed themselves, but I think God fixed it because He enjoyed it and found pleasure in offering a way to salvation and reconciliation.
For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be
thrones, or dominions, or principalities, or powers: all things were created by him, and for him
Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created.