Are we to literally take the account of Eve eating a piece of fruit as the reason mankind deserves to die and suffer in hell? Thanks.
The genre of Genesis 3 is narrative. The content of the chapter records historical events. There is nothing in the chapter that suggests any content is to be understood symbolically or figuratively.
When it comes to Adam and Eve’s sin, what is more important than the content of God’s command is the command itself. What I mean is this: God could have commanded Adam and Eve not to do something else, and their violation of that other command would have amounted to sin. “Everyone who sins breaks the law; in fact, sin is lawlessness” (1 John 3:4). Transgression, another word for sin, means to step across a forbidden line.
Martin Luther addressed your question with these words: “To reason it seems very ridiculous that any one fruit should be so deadly as to destroy the whole human race in infinite succession, and destroy it, moreover, with eternal death. But this power of destruction did not lie in the fruit. To be sure, Adam sank his teeth into the fruit; but in reality he sank them into a thorn, which was the prohibition of God and disobedience to God. This is the real cause of the evil, to wit, that Adam sins against God, whose command he ignores. He follows Satan. The tree of knowledge of good and evil was a good tree, bearing the choicest fruits, but because the prohibition of God is joined to it and man does not heed the prohibition, it turns into the deadliest of all poisons.” (What Luther Says, Volume III, Page 1290)