You're funny. The plain reading is that he will die on that day. Like as in literally dead gone. You aren't even reading the text literally. And changing the word day in Genesis 3, yes it would imply that gee, maybe those days in Genesis 1 weren't literal days then.
Who was Cain so afraid of? All of Adam and Eve's thousands of kids that were really bad sinners that got kicked out of the Garden?
And I suppose this:
And since you post very quickly:
Day 3 of Genesis 1 says trees
Genesis 2 says no shrubs then the pop up. But when did God make the Garden, when he made man? So that means God made the trees again on day 6. Same with the birds that it says he made again in the Garden on day 6. But Genesis 1 says birds on day 5.
And the lesser light rules over the night. I wonder what light you see in the nighttime that rules over the night like the sun does in the daytime.
I mean all of these with love in my heart.