Does water vapor in the air oxidize copper?
Although $\ce{H_2O}$ contains oxygen, it is there in the most reduced state $\ce{O^{2-}}$ and therefore cannot act as oxidizer. It is the oxygen in the air $\ce{O_{2}}$, which is the main and strongest oxidizing agent.

On the other hand, presence of water as a solvent can speed up some reactions. For a short overview of copper corrosion, see e.g. Why does copper oxidize. As the corrosion products form compact (or even protecting) layer, the corrosion itself is not a problem for copper, as compared to e.g. steel corrosion.