Why did God make it a sin to eat an apple? Eating a fruit* is not even a real wicked deed like killing somebody or something. Why did this whole sin thing get started with something so innocuous that by today's standard it wouldn't even be considered a sin?

* I'm pretty sure it was a fig.
There was probably no power at all in the fruit. The issue was that God gave them a choice and they chose to disobey Him. And so sin, in this case disobedience, entered the world.

I suspect that it could just as easily have been a, "Wet paint, do not touch!" sign.