"Well, the oldest rocks from the moon are around 4.65 billion years old and we can't tell the exact age of earth from earth rocks because they have been recycled throughout the years and now we have claims of water present on earth some 4-4.5 billion years ago so why are the moon rocks so dry if they came from earth?"

As far as I know the oldest Moon rocks are 4.5 - though it's quite possible there is some dated to 4.65. But 4.5 is close enough for me unless I get some information the allows me such confidence to saying it's as accurate as 4.65 billion implies.
As for your question. If the Moon was a swamp 4 billion years ago, it would as dry as it is today. And the Moon is being constantly hit with impactor and some of these impactor are fairly wet- say 25% of their mass being water. So over millions of years the Moon has had swimming pools- to small lake quanities of water impacting it's surface, some of the water immediately leaves the moon at higher escape velocity and most evenually leaves by the water vapor simply gain enough velocity due to heat to escape the Moon gravity. And a small percentage of this water finds it's way to lunar poles, and here in constant nite and extreme cold it stays.

"If a impact of earth caused the moon to form it would have happened before our current estimate age of the earth and moon."

Right. If the oldest Moon rock is 4.65 billion then the proto Moon would have impacted at this time [the moon would re-form very quickly- probably in decades to centuries]. The reason we have not found earier rocks on Earth is because Earth has plate tectonic and has resurfaced itself over the billion of years [also why we have less craters from impactors on Earth]. Finding a rock on Earth which is 4.65 billion would very rare- whereas on the Moon it's vastly more common. Note it is possible that rocks older than 4.65 billion could be found on the Moon or Earth- they simply survived intact traveling from Space.