To the contrary, socialism can only work at scale. Small-scale cooperation exists, yes, but isn’t really “socialism” as we understand it. A business cannot be “socialist,” socialism is a descriptor for an entire mode of production, not a quantum unit of an economy. Socialism is a mode of production where public ownership is the principle aspect, and regularly is proven to be superior to capitalism. The largest economy in the world by PPP is socialist, the PRC, and it’s a broad, diverse, multi-ethnic society of billions.

I think you’d do well to research more on socialism. “Human tribalism” is more of a response to immediate conditions within capitalism, a system dominated by private property. It isn’t some eternal genetic fault in humans, over time we have become increasingly interconnected and interdependent. Socialism is the natural evolution from that point now that capitalism has already centralized the broad majority of production, meaning coherent and deliberate planning of the economy is more feasible.