What is the wisdom behind the creation of jinn and humans for the worship of God, even though His worship does not increase His dominion and greatness, and based on that, Paradise and Hellfire?

Allah Almighty created humans and jinn for His worship. Therefore, a human's failure to worship Allah Almighty renders him lower than an animal. Since worship is a right belonging to Allah Almighty, He is deserving of it by virtue of His Lordship and perfection. It is an end in itself, not merely aiming at self-improvement.

Worship plays essential roles in a human's life: it reminds a person of their soul and its nourishment, that they are mortal while Allah is eternal, and it frees them from worshipping anyone other than Allah. It also liberates a person from vices like stinginess and cowardice, transforming them into someone adorned with virtues.