Yes, to see the effect of water vapor on temperature compare the daily highs and lows between Los Angeles and Death Valley. Same latitude, same elevation, same atmospheric CO2, drastically different daily highs and lows.
There is no positive feedback loop for CO2. Increasing CO2 in the atmosphere doesn’t cause increasing CO2 in the atmosphere. There is no mechanism.
Atmospheric CO2 does have a slight negative feedback. Increasing temperature expands the zone and seasons of plant life. Increasing temperature increases atmospheric moisture which increases terrestrial moisture. Increasing range, temperature, and moisture increases plant life. More plants scrub more CO2 from the atmosphere.
Don’t forget that we are emerging from an ice age, the argument for AGW is that there is an AGW signal imprinted in the temperature increase due to emerging from the ice age. That’s the ancient hockey stick argument. The hockey stick has since been disproved, it was an artifact of heat islands (development around once pristine temperature recording stations).
There is a weak argument that thawing Arctic tundra is releasing methane (CH4) into the atmosphere. Methane decays with UV light into CO2. Which is true . . . but those soils didn’t form frozen. What happens when Arctic tundra thaws into swampy land with all the added plant life? Swampy lands sequester more carbon into the soils (swampy soils are black because they hold lots of carbon).