In other words, giving thanks is part of our being/essence, not just a behavior that we pick up.
So (to translate inclusively): “In this action [of giving thanks to God] alone are we human beings” (pp. 170-171).
Barth goes on and on from there in his characteristic way, examining the ontological nature of human beings from a Christological standpoint. But I’m always struck by that idea of giving thanks as an aspect of human being.
Is it too much to say that giving thanks is as much our essential nature as our biological aspects (for instance, being bipedal not quadrupedal)? God made us this way: to be thankful to our creator and redeemer.