Are Humans good or Bad?

Whenever I hear the issue raised of whether human nature is essentially good or bad, I feel the question is misplaced. It seems like asking whether cats are essentially good or bad.
We have evolved certain tendencies which are good in some circumstances and bad in others. In modern life, many of the features which may have benefitted us while living in the plains of Africa 100,000 years can now be a hinderance, such as our almost insatiable appetite for sweets and fats. When we lived life as hunters and gatherers, it was difficult to accumulate material goods, and so being in a state constant craving for more and more likely served us well. This perpetual craving was necessary to stay alive. Since the invention of agriculture and much more so with modern technology, this state of constant craving leads to excess and waste. But is this something that can be held against us? Is it a moral failing for our technological advances to occur far faster than the rate of evolution? Can humans be held responsible for having evolved particular tendencies over millions of years, some of which can be destructive to ourselves and others, particularly when in a different context than those tendencies evolved to be helpful? I don't believe this judgment is anymore fair than it would be to condemn a grizzly bear as evil if you let it run loose in a mall and it eats people or a bunch of large pretzels. Yes, the bear may end up with a stomach ache and the pretzel shop owner is now without pretzels or life, but the bear shouldn't be blamed for following desires which are otherwise beneficial, but within that context were harmful.
I am not trying to say that certain human tendencies and actions are not harmful and destructive, because some are. But in general, they are harmful because of context. In the context within which those tendencies evolved, they were beneficial, otherwise they would not have evolved.
There are very few tendencies which might be seen as destructive regardless of the context. A person who today might be a regarded as celebrity because of their joke telling ability may have, in the past may have been regarded as serving little purpose. At the same time, someone who today may be seen as quick to anger or a brute may at one time played a valuable role in the survival of his tribe.

If we had none of the traits we today regard as the failings of human nature, it is unlikely any of us would even exist today, because at one point in time those traits were necessary for our survival. To regard humans as bad, or even good, for maintaining tendencies which were necessary at certain points in time for our survival, some of which are now destructive because of our radically changed environment, is, I believe, an unfair and misplaced judgment.