Are we all just exchanging energy?

I am not sure about exchanging it, but of course energy can be neither created nor destroyed, only converted or transferred.

I suppose we are in a sense, since the data behind all our conversations here are streams of electrical pulses (and light, where conveyed by glass fibre-optical cables). Though we don't bounce it back. We simply send another packet of energy in return.

Garage sales would indicate that we mostly exchange children's clothing & toys, and kitsch.

If we consider that information also can't flow without energy, then yes..