Jesus sacrifice on the cross?

What if it wasn’t Jesus one-time takesie-backsie “ultimate” sacrifice that atoned for humanity’s fall, but the past, present and future abuse of our fellow species and our own is actually a full display of our unredeemable wickedness? We never were our brothers’ keepers, never accepted that assigned role, at best faked it from time to time, and frankly we are simply incapable of it by (intelligent) design.