"Circumcision" is a word we use to signify a spiritual event or condition. The word "circumcision" is not the thing-in-itself. It's merely a sign we use to signify the thing we label with the word "circumcision."
Brit milah is a ritual which, like the word ("circumcision"), merely signifies, or ritualizes, the spiritual event or condition we label with the word "circumcision," and which we act out ritually through brit milah. Neither the word ("circumcision"), nor the ritual (brit milah) are, or affect, the actuality the word and the ritual merely attempt to manifest is a visible or auditory manner.
In the Hebrew text of the Torah, the so-called "foreskin" (ערלה), is the masculine element of an otherwise female, or generic, human body. Removing a slice of flesh from the penis is, once again, merely to signify, or manifest, that the person where that slice of flesh is removed has, spiritually speaking, eliminated the offensive form of masculinity symbolized by the existence of the phallus (see signature at bottom of message).
Ritually removing a slice of flesh from the penis, i.e., brit milah, doesn't actually remove the offensive form of masculinity. It only symbolizes overcoming the offensive, literally toxic, form of masculinity. A person can remove as much of the penis as they like, even the whole thing, and not remove one iota of the spiritual toxicity the penis, and the slice removed from it, merely represent in a carnal manner. Consequently, a person can retain all of their penis, every bit of it, and still be truly circumcised since the word and the ritual are only the carnal signifiers of a spiritual condition. Since the word and the ritual aren't the spiritual condition (they merely represent the spiritual condition) the spiritual condition can exist without the ritual or the word.
This being the case, a baby can indeed keep the slice of flesh errantly called "foreskin" (ἀκροβυστία), and still have eliminated the toxic form of masculinity (the "foreskin") only symbolized by the penis, and which is only symbolically removed during the ritual when a slice of flesh is ritually removed from the penis. The ritual doesn't guarantee the reality that it merely symbolizes. You can have the reality without the ritual, and you can have the ritual without the reality.
John