The tree of knowledge of good and evil

Is our knowledge of good and evil the main thing that sets us apart from animals?

It's impossible to say if animals have these same concepts, I'm afraid. Primates have demonstrated they understand the concept of fairness, as have dogs, so it's not outlandish to say they might have something along these lines. For example, if you're a lion and you start eating other lions, you're going to be punished by your pride by either getting killed or being cast out, which is essentially a death sentence for a pack hunter. It's impossible to say that lions do this because they think such behavior is 'evil' per se, though. 

Yes, I have seen the monkey and the grape video, it really does seem like they understand fairness. But I am unsure if they can understand the concept of good and bad,aside what they want for themselves.

It helps not to think of it as "good" versus "bad," it seems a subtle distinction but try to think of it as "beneficial to the group" versus "harmful to the group" in terms of resources and reproduction. Good and bad are subjective terms, but beneficial versus harmful are far less so. 

Slightly off topic, but I wonder if the monkey would give a grape to a stranger who only got cucumbers....now, that would really show they understood fairness

I think the answer is no, cucumbers taste gross compared to grapes :). 

for anyone who hasn't seen the monkey and the grapes video

I love the part where he throws the cucumber at the lady lol

(yes I know I am a horrible person lol)

We do have very big brains - i's likely we can have deeper and more subtle thoughts than non-human animals.

Another factor could be that most non-human animals have pretty tough lives - personal survival may have to be prioritised more than in a human society which depends so much on co-operation.   Indeed, i wonder how robust human ethics are when we are stressed!

So perhaps morality is a luxury few non-human animals can afford.  On the other hand we humans have to have morality to prevent the socierty we depend on breaking down.      

if by evil you mean hurting others for your own pleasure or gain no they don't. Even when lions kill hyenas but don't eat them it's because they are a threat to the pride. Same for cats or whales that "toy" with live pray to teach the young the eat. Even vicious dogs act on training or instinct. 

I doubt  it is the "main thing". What isn't good to one human is maybe perfectly acceptable to others. Cannibalism for instance is abhorrently evil to most people here in the west and many other places but is still believed to be practiced in places across the globe.

I would suggest conscience or consciousness among many other things that separate humans from animals. 

By conscience, do you mean our ability to consider impact of our actions on others? Clearly animals are 'conscious' (as opposed to unconscious), but I'm not sure I agree with the ability to consider impact on others a strictly human trait. Our ability to extrapolate this consideration to much wider populations (i.e. future generations beyond direct offspring) might be somewhat unique, but all pack animals seem to have at least a rudimentary understanding of this principle.

Thus far in this discussion, it seems we're having quite a bit of trouble discerning exactly what separates humans from animals. I think it's because the answer is "humans are animals." When I was in school, they taught us that one distinguishing factor was our ability to make and use tools, until they discovered apes using sticks to get ants out of anthills or something like that. 

Humans are animals and we do not have knowledge of good and evil, unless you want to tell us that knowledge?

That's right Goldtop is all for child molesting if you want to cause no one cares it's evil if they are atheists. 

And an  imagination that I believe out-strips anything else living on the planet.

I did say among many other things. For instance, us humans do things that we do not need to do and that contribute absolutely nothing to our survival. Animals seem to only do what is needed to do for them to survive.

Examples would be a our creativeness in writing, art, drama and of course music, all unnecessary traits that we do not need to do, but do regardless. All this is opinion of course but just these few things appear to be unique only to humankind and again, in my opinion, set us apart from other animals.

Their lack of understanding would be the difference. If they can perceive the world as humans or be as effective as humans there is no real difference.  

I appreciate that you put the caveat "seem" and "appear" in this response, as it's impossible for us to figure out if a silverback gorilla is doing something other silverbacks see as 'art' for example. If we can't say for sure if they do have some sort of creative side, then we can't be sure we're separated along those lines. And as far as only doing stuff for survival is concerned, that's a fairly 'civilized' view of things. If you were in a jungle by yourself, I would guess the only thing on your mind would be surivival, food, shelter, etc. Our bandwidth for creative endeavours and other seemingly superfluous pursuits owes entirely to the fact that in most of the world, we've conquered the basic needs. 

And now some people cannot distinguish between their wants and their needs. Today almost everything (including bad ideas) is sold to us  a must have or need when it is anything but. Things are sold to us as a need through veiled fear too.

And barring a great catastrophe, this will probably be the death of humans imo.

No. It's only our superior level of knowledge that sets us apart.

Good and evil are merely conceptual assumptions, derived from knowledge.

The promise of the serpent was that eating the fruit would give us immortality and makes us as gods.

Theosis and immortality does not come from disobeying God's command, quite the opposite, we need God for this.

And so we have inherited the mess cause by this. We live in a world where it is easier to do evil than good. 

Western theology teaches that we inherited guilt from the garden. We Orthodox trace this error to a mistranslation in the Latin Vulgate,  and an over dependence on the teachings of Augustine in their theology.

What is actually the Orthodox position is that the sins of others do effect the world we live in, and that first sin of Adam was instrumental in creating the current environment that we find ourselves in.

We inherit the mess, not the guilt. Very different.

But to answer your question, what makes humans distinct is that we were created in The Image of God. In fact, this is what it means to truly be human. In fact, this is the belief that secures human dignity in the world.