Your forefathers ate the manna in the desert, yet they died.
The manna, which was the only food for the Israelites for the 40 years they wandered in the desert, could not prevent their physical deaths. All the grown men except 2 died during those 40 years. Nu 26:65
Nu 26:65 For the LORD had told those Israelites they would surely die in the desert, and not one of them was left except Caleb son of Jephunneh and Joshua son of Nun.