The question “Why?” is a false, prideful question. “Why is the sky blue, momma?” “The sky is blue because the chemicals up there are X, Y, Z.” “Why are the chemicals up there X, Y, Z, Momma?” And so on to infinite regression. There is no “Why.” There just is.
This is the fallout of Genesis 1-2-3. Why did God put that fabulous tree right in the center of the garden? Why did He populate it with such damn attractive fruit? He said it contained the mysterious “knowledge of good and evil?” Why did he have to go and say that? Unfair! Adam and Eve were in a 100% good Garden and would have no clue whatsoever what “good and evil” even means. God said that this knowledge would make them like “us” (the spiritual-heavenly bodies of Himself and His angelic crew.) They cannot know what this “us” knows, for they are human.
Just humbly accept that the forbidden fruit had to be there in the center of things. That is the way it is. Blue.
Along comes the Serpent: “Oh, you’ll be fine, Eve,” the Serpent says. “Here,” and she takes a bite. Boom! As soon as you listen to anything other than God, well … out, out, out from 100% good garden to struggle: toil, trouble, temptations, and not-knowing. Cover up your vulnerability, men. Cover up the lure you provide, women. Here’s a fig leaf (an apron)–one for each of you. Go! It is not so much that what you did is a Sin; it is being human. Why is being human like this? It is.
Out here East of Eden we still sense the Divine Origin, the mystery. We sense that there are principles to which we are to adhere to make life “work”. Our human minds incessantly try to know what God is, but our minds will never succeed. There is just awareness of a something at the center, holding it together–core, deeper, higher, more beautiful than anything. We are allowed into that awareness only with humility, not with knowing. Heck, we cannot even really know that we do not know.
Sirach captures our machinations when he says, “The sum of all our words is: He is all.”