Collective efforts exist due to the contributions of individuals. One person making a principled stand on how to live their life makes a difference. There are examples all over this thread, and even if you don't think something will last, it doesn't mean it isn't worthwhile to support it in the moment.
The obvious response to your request is "do nothing". And don't let anyone sway you otherwise.
I asked for examples, I don't know what you're referring to in the rest of the thread. Sure collective efforts work because of individual contributions. But I believe you can only change things collectively and asked you for an example where a single person was able to make lasting change.
I just think the individualism narrative has become dangerous, because it leads to people's refusal to participate in collective action. Or it leads people to believe they are not the "right individual", that they don't have what it takes to be the person to make change, and therefore they end up doing nothing. I don't think the collective approach leads people to "do nothing" but quite the opposite! There is no one who is "unfit" to contribute to collective action. The more people involved, the more powerful it is.
The obvious response to your request is "do nothing". And don't let anyone sway you otherwise.