This is how it has always been throughout history (and still is in most parts of the world).
Individual is part of nuclear family, nuclear family is part of extended family, extended family is part of tribe, etc. When one part is in need, the others jump in to help.
Wasn't "nuclear family" something marketers invented in post-war USA to sell more houses?
> throughout history
Ancient egypt? Roman times? Medieval times? Byzantine times? Pre-colonial Philippines? Pre-colonial America?
I think it may have started in the late 1800s at the earliest. I would need a bit more evidence to be convinced that your model of individual to nuclear to extended etc has been a thing longer than a few centuries, vs the vast majority of human life experience being in nomadic hunter-gathering, villages, farmland, and walled city-states. We just had clans which were all our family. A fellow villager wasn't much different than a cousin. The individual and nuclear family, not so much a thing.