The tree of life predicament

Genesis 3:21-23

Then the Lord God said, “Behold, the man has become like one of Us, to know good and evil. And now, lest he put out his hand and take also of the tree of life, and eat, and live forever”— therefore the Lord God sent him out of the garden of Eden to till the ground from which he was taken. So He drove out the man; and He placed cherubim at the east of the garden of Eden, and a flaming sword which turned every way, to guard the way to the tree of life.

I guess I didn't catch this before but apparently there was a "tree of life" in the garden of Eden. It seems that if Adam and Eve would have eaten it after they sinned they would have lived forever.. I guess I'm a little confused . Why would Jesus have to die if they could have just eaten the fruit of the tree of life and reverse death's grip?

Let me know what you guys think..