It is said that man is the supreme being among all creation. What does Judaism say about this?

The best way to understand Judaism's dual approach to this question is to look closely at the two different creation stories. In Genesis 1, God creates humanity as the culmination of the created order. And then God commands the first humans to be in charge of everything: “Fill the earth and master it; and rule the fish of the sea, the birds of the sky, and all the living things that creep on earth” (Genesis 1:28). The message here seems clear: humanity is created to dominate the world and the rest of the created beings. 

Contrast that, then, with the message of Genesis 2. There, man is created after plant life but before the animals. And then “The LORD God took the man and placed him in the garden of Eden, to till it and tend it” (Genesis 2:15; other translations have “to work it and keep it”). Here, man is created to be the steward of creation, the caretaker appointed by God to oversee the garden.

One story suggests domination; the other, responsibility. The rabbinic tradition grapples with this tension. On the one hand, humanity is seen as the only moral agent in the world, therefore worthy of domination of the created order. On the other hand, limits are set up around the extent to which we humans are allowed to exploit the created order for our own benefit, for "The earth is the LORD’s and all that it holds, the world and its inhabitants” (Psalm 24:1). Jewish tradition imposes limits to man’s dominion in the following categories, and more: the slaughter and eating of animals; the destruction of trees during wartime; the treatment of animals used for work; the treatment of lost or injured animals; the provision of rest for farmlands and the corners of fields for the poor and needy.

The words of Psalm 8 (v. 4-10) echo this duality:

"When I behold Your heavens, the work of Your fingers, the moon and stars that You set in place, 

what is man that You have been mindful of him, mortal man that You have taken note of him,

that You have made him little less than divine, and adorned him with glory and majesty?

You have made him master over Your handiwork, laying the world at his feet, 

sheep and oxen, all of them, and wild beasts, too; 

the birds of the heavens, the fish of the sea, whatever travels the paths of the seas. 

O LORD, our Lord, how majestic is Your name throughout the earth!”

Somewhere between divine beings and the lower animals, we find our place within the created order. We are but dust and ashes, and yet we are created in the image of God. Both sides of this coin together complete the Jewish picture of humanity, calling us to self-respect and humility, responsibility and gratitude.