Your statement is slightly misleading.
Water vapor - i.e., gaseous H2O - is a colorless gas, just like carbon dioxide or O2.
Clouds are regions of the atmosphere in which the water vapor has (at least partially) condensed out, forming tiny droplets of liquid H2O which remain suspended in aerosol form.
Normally, we are surrounded by air containing water vapor - but since it's colorless, we don't see it.
The above explanation is likewise an oversimplification, but I think that it comes at least a little bit closer to the truth.
Regards,
The molar mass of H2O is less than the molar mass of O2, which is less than the molar mass of CO2. Unless that changes, CO2 isn’t going to trap heat in the atmosphere.
It will continue to help plants develop in the ocean.
That was the point.