Well, they ARE in trouble if they think any of God’s commands are insignificant. If He tells you how to comb your hair, you’d BETTER do it that way!
What I mean is that the fruit from the Tree of Knowledge was the smallest possible sin, in the overall scheme of things, that man could commit. If Adam and Even had refrained from touching and eating the fruit, we would have maintained a sinless world because we wouldn’t do other sins that are worse than that. It’s a gateway sin, so to speak.
I don’t think that we will be the last creation in a deathless and future sinless universe. If there are other creations, they will have their own tests of their smallest possible sins that, if avoided, will help maintain their world to be a sinless one.
You and I, having intimate knowledge of just how things can get in a world of sin, we would be well qualified to teach new creations why they should resist their gateway sins.