The Son of God became "man," and not "a man."
And yet, when Christ stood before Pilate, a man and a God in fact stood before him. And Pilate spoke truly when he said, "Ecce homo", which is correctly translated, "Behold the Man."
Although some, in a false spirit of equality, may be tempted to translate the Creed, "for us humans...became human," this seems to be too abstract and far less incarnational--ie, Christ had real flesh and real bones--indeed he was a truly a man. And again, earlier in the Creed the believer professes his belief in the "Son of God." Man cannot ignore, therefore, that the Word became flesh as a male, as the son of Mary and the Son of God. He was a man and yet in Him he encompasses all mankind, just like the first man, from whom all mankind, including Eve, came forth.
It certainly cannot be said that the Fathers who drafted the Creed thought of Christ as if in some scifi movie observing a strange looking creature and exclaiming, "Look, it's human!" No doubt what is clear is that Christ was a real man, "the Son of Man," not the "Son of Human". As Liturgicam Authenticam reminds us,
When the original text, for example, employs a single term in expressing the interplay between the individual and the universality and unity of the human family or community (such as the Hebrew word �adam, the Greek anthropos, or the Latin homo), this property of the language of the original text should be maintained in the translation.
The word, "human," does not convey the same interplay between the individual and the universal, because it refers too abstractly to the universal without the concrete meaning conveyed by the term "man".