"The greatest trick the devil ever pulled was convincing the world he doesn't exist." --Charles BaudelaireI believe the first thing to realize is that Satan isn't some pseudo-deity out there but our own "sinful nature". Note that animals can't be evil just humans.
I believe it is part of us being gods. We have the ability to be a creator or a destroyer. The choice is ours, not God's, Satan's or even Jesus'.
What ever we are, we can only blame ourselves.
I can agree that none other are responsible for our own thoughts, actions, reactions, and speech. The devil will pay for his own transgressions, as well. And one of his transgressions is introducing transgression to the world. Had he not introduced transgression to the world, our only so-called "experience" would be merely a concept. When the devil tempted Eve, it was more than just knowing good and evil that he offered, but experiencing good and evil more than anything else. The proverbial "fruit" of this proverbial "tree of the knowledge of good and evil" must have included guilt, as the first chosen couple must have experienced guilt after first experiencing disobedience.
I guess my point is, I believe it's unwise to disregard what's written as true even to a minor degree, because of a surety, man would not have limited himself as to what was considered acceptable and unacceptable, and civilized and barbaric. There were many cultures that accepted what's called "fornication" in the bible, and they flourished as a society and civilization. Man, alone, couldn't and can't discern what's truly "righteous" and "evil." And as far as animals are concerned, they can't be "evil," because animals aren't prohibited as people are, by any prescribed law. But, if we were to label animals as such, it's been proven that animals, indeed, have an "evil" nature, as well.
Thank you for your time and consideration.