In keeping with later teachings, God likely sacrificed a sheep or a lamb as a preview of the eventual sacrifice of the Lamb of God who would take away the sin of the world.

(yang / sheep, lamb, ram, ewe)
The Chinese characters have it perfectly correct, showing a lamb (yang / sheep, lamb) covering me (wo / me) gives me (yi / righteousness) in God's sight. Jesus Christ is that sheep (Lamb of God; John 1:29), sacrificed for us.

(yi / righteousness)

The character for (wo / me) has a hand and a spear at its side. Perhaps that reflects the sinful nature of mankind - a killer.
(shou / hand)
(ge / spear)
(wo / me)

Jesus Christ's side was pierced by a spear to confirm his death. That was predicted a few hundred years earlier when the prophet Zechariah quoted God, saying "They will look on me, the one they have pierced..." (Zech. 12:10)

The simplified character for righteousness has no resemblance to the earlier characters. Yet the small line at the top is a drop of blood. The crossed lines can be either a sacrificial cup or firewood used for a burnt offering. The modern character still has a relationship to a sacrifice to purify us of our sins.