Do you think that early hunter-gatherers shared their food with people who did not participate in acquiring food?
Without capitalism, we could regress to the most primitive version of civilization and still require contribution to the tribe. The alternative is to go off on your own (and at that point, there are no "people around you" to help). Less primitive alternatives, as different political-economic systems, usually still require you to contribute through taxation.
I don't think this is true. This is one of these work ethic corollaries that helped build wealthy societies when productivity was proportional to people's effort. But it seems to grow more obsolete by the day.