We aren't directly putting more water vapor into the atmosphere, but a warmer atmosphere can hold more water and (I would think) would also increase the overall

We aren't directly putting more water vapor into the atmosphere, but a warmer atmosphere can hold more water and (I would think) would also increase the overall rate of evaporation. Regarding the greenhouse effect of water vapor, I don't know whether what matters is the average relative humidity or the total amount of water vapor in the atmosphere. For our sake I hope it's the former.