Empathy among one's in-group is certainly normal. Even hitler loved his dog. But empathy for one's out-group is a rare exception. And it's not altruism unless it encompasses one's out-group.

I think your vision of a potential society seems nice. And that it would only be possible to establish and maintain to assure perpetuity if there is some formalized system of governance to define precisely how aid is rendered, how needs are met, and what the mutual rights and obligations of each member entail.