Sure it is. What do you think Nicodemus was asking about? He specifically asks whether the second birth was to be like the first, from the womb. He took one birth to be the natural one, and he didn't know what to make of this second birth. Since abortion was not an issue then, of course one would have to be physically born in order to enter heaven. That was a given, but what is this second birth, wondered Nicodemus. Jesus, sensing this, answers him including both births, one of water (physical birth) and one of the Spirit. He doesn't say "again" here because this is the only place He specifically separates and names each birth. Then in verse 7, He mirrors verse 3 and condenses them back together again.
You read John 3 in isolation from the fact that St. John the Baptist has already established a form of baptism that created a link between immersion in water and spiritual rebirth, which, of course, echoed the Flood and the passing through the parted sea in Exodus, -- all prefiguring rebirth through baptism. It also ignores Matthew 28:19, where baptism -- the word itself implies water, -- is proclaimed necessary for Christ's plan.
Moreover, your interpretation forces Jesus to mix up a second metaphore of physical birth to the total of three. I thought you were a believer in the perspicuity of the scripture. Consider how, according to you, Nicodemus refers to the physical birth, with great clarity, as birth from the womb in verse 4; Christ in 6 calls is birth of the flesh. But in 5, according to you, Christ abandons the "womb" terminology already offered by Nicodemus in favor of the very unclear "birth of the water", especially unclear in the context of both baptism of John and the scriptural context. In 6, however, Christ already speaks of "flesh". Why did He not stick to the "water" terminology in 6?
Lastly, you agree that the physical birth is "a given", -- we are not in the business of saving souls not yet made, and the unborn babies are not in view of the discussion. So why would Christ state the necessity of physical birth so forcefully, if that is what He is referring to in 5? Nicodemus asked Him about the second birth, not the first.
This is a good example how do-it-yourself scriptural exegesis produces disagreement over a core Christian belief.