An important consideration is time. Its doubtful it took Adam long to sin.
2. Experiencially, Adam was not familiar with "death" because there was no death in the animal kingdom and of course with man
Hmmmm Since Adam didnt keel over and quit breathing, is it possible that 'death' as used refers not to death in and of its self, but the death of a human being,in a way the entire race of humans, having eternal consequences?
There is also the question of microbial life, some modern microbes life span is measured in hours.
God fashioned herd animals and predators, thousands if not millions of various types of predatory insects.
Every animal and every bug and many microbes were designed to sustain themselves through consumption. Obviously if you pull a carrot up out of the ground and eat it ,its dead.