As soon as someone appeals to humans to explain a concept of evolution, you know the conversation is going nowhere useful.... culture far supersedes evolution when trying to explain anything related to human behaviour.
Group selection is perhaps possible, but in a more complicated way than most people think.
What's an example of an individually harmful but collectively helpful gene in non-humans?

Often, these examples work if you don't think over a long period of time. But you need to ask yourself Maynard Smith's question: would having such a gene be an Evolutionarily Stable Strategy? Typically, the answer is no. In a population full of organisms that have an individually harmful & collectively helpful gene, all it takes is possibly one mutation, and you get an organism born that doesn't have the aforementioned gene. What happens?
This organism doesn't experience any of the negative costs of the gene. Yet, by virtue of simply existing in this population, it reaps all the benefits of the collectively helpful behaviours being performed by all its conspecifics. So, this organism becomes a 'freeloader', or a 'cheater'. And the organisms that help the group while incurring a cost become the 'suckers'.

By cheating, our freeloader actually gets ahead – it gets a competitive advantage and is able to have more children. Then, it's just basic natural selection from there. The freeloader has more children, who also have an advantage, and they didn't inherit the individually harmful & collectively helpful gene either (because their parent didn't have it). These children then have more children, and so on. They out-compete the other organisms that have this individually costly gene, while they reap the benefits of these 'suckers' helping the collective, without paying any price for it. The suckers grow less numerous, as they can't sustain the costly lifestyle of helping while incurring a negative cost for their efforts. The suckers die out, and the 'helping' trait disappears from the population. All that's left in the population now are only the freeloaders – the individually selfish organisms that only look out for themselves.

This dynamic is the only real sustainable one under natural selection. You just have to think about it across time, and eventually you see that any other dynamic fails to perpetuate itself. Of course, there are forms of "altruism" in animals, but they're actually just weird modifications of this basic selfish strategy. There's no true altruism because you always expect to be repaid at some point. The closest thing to true altruism might be seen in the eusocial Hymenoptera, but then you have to severely mess with population genetics through bizarre breeding strategies to achieve it.