"I think most of us as individuals could lead happy and fulfilling lives and contributing to the advancement of humanity without any of that." Your assumption

"I think most of us as individuals could lead happy and fulfilling lives and contributing to the advancement of humanity without any of that." Your assumption is that we led happy and fulfilling lives before what we now call society, which is false. Bad harvest years would routinely decimate communities. Hunger also drove people to steal from others, many times violently (kill, rape, and ransack), and in the best case where they only stole your food, you were now left to starve because a famine affects everyone, and the victims were already on rations as it were. Local spots of violence in the struggle for the very few resources that we had were very common place. As societies evolved, such conflicts for resources became more necessarily more complex (think bands, think small militias, think city-state armies, think all out war). The main misconception I tend to see people have is that they somehow believe that our current condition is somehow different from the condition we were in. As if society was imposed on us and we became bad. We are society. Be it a community of ten or a community of a thousand. Good an evil are both sides of the same coin, it's just our nature.