God cursed the ground, and the terms of the curse were specific, and had nothing to do with living forever.
In the garden, all that Adam and Eve had to do was stretch out their hand to any tree, and all of the fruit of all of them was good for them. They did not have to work, to cultivate, at all. They were gardeners - dressing the garden. They were not farmers, tilling the soil. The former is a creative, artistic activity. The latter is hard, hard work.
At creation, the animals were given the herb of the field. But when placed in the Garden, specifically there, Adam and Eve were given the fruit of all of the trees to eat. They weren't in there planting vegetables, doing work.
Then came the fall. NOW Adam and Eve would eat "the herb of the field", NOW he would have to gain his bread by the sweat of his brow. NOW, outside the Garden, they would be in a world where, instead of EVERY tree being fruit bearing and good for food, most plants were not (and are not) good for food.
And God made it harder than even we have it, for he specifically spat on the ground (the word we translate as cursed literally means "spat upon") so that it would bring forth thistles, thorns and noxious weeds when Adam sought to plant it and scratch a living out of it.
That was the curse of the soil. It is described very specifically. And THAT curse was also very specifically removed by God after the Flood. It was not as hard, after the flood, to grow food from the ground. The ground was no longer perversely opposed to man, throwing out thistles and thorns. Sure, there are still weeds, but those are randomly arising, as opposed to the hostility of cursed ground that will push out thorns and thistles when Adam tries to cultivate it.
In any case, God himself says after the Flood that he will no longer curse the land, so if I'm to take Creation, Adam, Eve, the Fall, the Flood and the Ark literally, I'm also going to take that end of the curse literally as well. I can see no other way to read that language. It's pretty clear really.