Skins. Not leaves.
God provides acceptable
covering
"The Lord God made garments of skin for Adam and his wife and clothed them."
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God covered the nakedness caused by sin in the only acceptable way -- through bloodshed.
After they had disobeyed God, Adam and Eve discovered their nakedness for the first time. It was the first appearance of fear, shame and embarrassment.
In an attempt to cover up, they sewed together fig leaves as a garment.
Unfortunately for them, this effort was not acceptable to God. Instead, God provided the proper covering. -- skins from an animal. Unfortunately for the animal, this required bloodshed and death.
It set the standard and the precedent for future sacrifices that are acceptable to God.
God will provide a ram for Abraham sparing Isaac, set the requirement for the Passover in Egypt saving the firstborns, and ultimately Jesus' crucifixion as the acceptable atoning sacrifice for mankind.