Deep subject Farkel and an excellent way of presenting it!
As biology student I tend to look at this problem from a biological perspective.
First of all it really depends on how you define 'good' and 'evil'. Usually 'good' is defined as conforming to the group or society one is born in. 'Evil' is then defined as subverting from this conformation. The good one works with the system in a give and take manner, the evil one works the system more like a parasite. Since the urge to conform is very strong in the human tendencies (we are a flock- or herd like species) this would answer your question that humans are born 'good'.
In nature we see that in populations both 'conformers' (the majority) and the 'cheaters' (a minority) survive. Both strategies work. However, the cheaters can only exist because of this majority that conforms. Calling one of them 'bad' seems nonsense because one group creates the possibilities for the other. In the struggle to survive their are no rules. What matters is reproductive success. The strategy to reach such success is neither good nor bad. Just different roads to the same destination.
Just as in nature their are also 'cheaters' in the human population. But I think comparing the two is meaningless because we as humans are self-aware which makes a huge difference. What works best in our society is to conform to rules that equals the chances of survival for each individual. We see this as 'good'. Example: love, sharing. Intentionally harming another's chances is then seen as 'bad'. Example: stealing, murder.
Just my two cents,
Greven