Had Gadya: What's Radical about the Rhyme We All Love for Passover?

...For in the month of Nissan everything was ripe for redemption as indicated in Torah, but the malfunction that happened through distorted justice was not rectified during the moment of the exodus. Had Gadya reminds us that the events related to Passover--the redemption from slavery and exodus from Egypt--were enactments of divine justice in the world. It was God's hand, not ours, which punished the Egyptians. Even so, the revelation of Divine Justice was only partial. The Passover Redemption that happened in haste was incomplete, only a beginning, a foretaste of the ultimate Judgment. Our collective and individual perception of justice is incomplete (even though this rhyme tries to spell it all out!). And we remain in exile and incomplete. But, in the end, God will show us that divine Justice does reign in the world: God will slaughter the Angel of Death and bring the Messiah. But for now, reparations are still incomplete...

Chad Gadya, Chad Gadya: It is possible that even with all the promises contained in the Haggadah, the Jewish people were still disheartened and discouraged about their future. After all that transpired in Egypt, all the ways in which our ancestors prepared to leave Egypt (so that even a slave saw more at the Red Sea than Ezekiel saw in his prophetic visions), and even though they stood at Sinai, the people of Israel quickly succumbed to sin. We see this in Scripture: While the king was on his couch, my perfume gave forth its fragrance,” – and all of Israel‟s repairs were spoiled, and, “I have taken you for divine beings, as sons of the Most High, all of you; but you shall die like as men do, fall like any prince.”
Since (Israel so failed in the time of the Exodus) we have reason to worry about the promises of the prophets who tried to comfort Jerusalem and Zion and the chosen people and allowed us to foresee God's future redemption wherein "the moon would shine like the sun," and "God's name would be one," and “neither shall the children of wickedness waste them any more, as at first.” Could it be that all these repairs will only last a day or two and then Satan will come to dwell among us to destroy and uproot all the repairs as happened in the time of the giving of the Torah at Mount Sinai? If sin caused our ancestors to destroy whatever repairs they had performed, God forbid the same may happen to us. For all this our hope would be lost, and therefore the Maggid comes to comfort us with Chad Gadya.
We learn here that all the repairs and preparation were not carried out by God but by human beings, and just as a human beings are transient, so too their deeds are transient. In the future, however, the repair of Israel will be performed by the Holy One himself, and just as God is eternal, his repairs are eternal as well. Then God's promise will be fulfilled, “and I will remove the stony heart out of their flesh, and will give them a heart of flesh.”

With this we begin Chad Gadya. What exactly is the significance of the "single kid?" Chad Gadya. is a symbol of the free will for which the world was created. God created all things so that there are opposing choices. God created the good and evil inclinations and He gave us a choice between them.
We see this in the symbolism of Yom Kippur. The Torah tells us that, “Aaron shall take two he-goats and let them stand before the Lord at the entrance of the Tent of Meeting.” Why were there two goats? The two he-goats symbolize the good and evil inclinations which are in all human beings. Each tries to advise, one toward good and the other toward evil. But because they are so much alike, we cannot tell them apart. Similarly, we cannot differentiate the two goats on Yom Kippur.
They look alike in all – in height, appearance and color – so that they are interchangeable. We can only tell them apart by drawing lots – one is then designated for the Lord while the other for Azazel.
Similarly both the good and the evil inclinations must serve God, just as these goats do. When we draw lots, we learn that our good deeds lead us to God while sin leads us to Azazel. Yet the goat that is sent to Azazel is also necessary for our repair. The scapegoat upon which the priest confesses our sins also serves a divine purpose since it carries away our sins. In this way, both the good and evil inclination must serve God.
The two goats of Yom Kippur are symbols for the two inclinations in every human being. Similar to the two inclinations, both goats are used in the service of God. One was sent off to Azazel to die, and the other one became a sacrifice to the Lord. Since we cannot tell the goats/inclinations apart, it is easy to confuse them and the one for the Lord must also be sacrificed while the other is led off into the wilderness. Therefore we choose lots so that one is designated for each purpose.
Before Adam sinned, everything was sanctified to God. But once humankind sinned, good and evil became mixed together and “Sin coaches at the door.” The two goats of Yom Kippur are like the twins, Jacob and Esau. In the opening refrain of Chad Gadya. we say that Father bought the goat for two zuzim; we repeat this refrain twice because in fact he bought two goats for one zuz each. We repeat the words Chad Gadya. twice as a reference to the two goats of Yom Kippur and the two inclinations. A righteous person who serves God properly uses the evil inclination to turn darkness to light and bitterness to sweetness.
So too when the Jews left Egypt we find that this was the case: The Jews did not abide by their faith very long after they left Egypt. The Torah says, “they tried the Lord, saying: "is the Lord among us, or not?" The evil inclination overcame them and caused them to doubt God‟s providence.