Please let me know if this community is not the best place for this post.
When I was a teenager, and even in my twenties, I used to be quite idealistic, naive, and somewhat radical, believing that all humans have the capacity to be good, and that the only thing preventing utopia where all live in abundance were the historical shackles of national/cultural/religious identities. As in, humans would for sure all get along, if only there were no major reasons for any "us vs them" type thinking.
But the older I get, the more my thoughts on the topic have shifted. My idealism has constantly been worn down by finding out about more and more people who would be happy to fuck over every single other person on this planet if it meant they could get a bit further "ahead" than everybody else. But even on a much smaller scale, after establishing my own family and building my home, at some point I realised that I would personally also be willing to go to extreme lengths if necessary to protect the way of life of my loved ones, including picking up a gun if our neighbouring country decides we should no longer have our freedom - this is something I would have considered "idiotic patriotism" when I was younger. Basically, this means I would also be willing to fuck up the lives of others in order to improve the lives of my family, and I think the same is true for most people.
What I'm getting at is that I think there are lots of reasons that people can have to hurt other humans, ranging from psychotic greed to a strong commitment to close ones. I think this is just human nature. I'm using the word "hurt" here in a very broad sense, including taking advantage of somebody, etc.
If indeed this is human nature, and humans are willing to exploit others to try and improve the situation for themselves and their loved ones, how can communism work? Would we not need to "evolve" to a new stage of humanity first, where people are capable of putting the needs of society above their own desires?
I apologise if this is a dumb question with some obvious answer, I admit I have not read any books on communism and am probably missing some key points.
The Confucian philosopher Xunzi argued that humans are inherently bad, but it's precisely the inherent badness of humans that we should put immense thought and care into our ethical and social systems so that the few good parts of humans are cultivated and humans become good. This is what's fundamentally missing in your analysis. Whether humans are inherently good or not is a different question from how humans can become good and what responsibilities humans have with each other and with the rest of the world. Nothing is static, and as conscious actors, we have the power to shape our environment, including ourselves.
No human should die from malnutrition and starvation. This is a goal humanity ought to achieve. Human nature only factors in to predict how easy it is to accomplish the goal. If humans are inherently good, feeding every single human is largely an agricultural and logistical problem with an agricultural and logistical solution. If humans are inherently bad, then feeding every single human becomes a long and arduous struggle to root out callous apathy and malevolent actors. But the war against hunger still has to be waged, even if the fight is too hard to be won.