John is to the New Testament what Moses is to the Old Testament: a simple and plain writer, and a distant, lofty, and unbiased historian. He has a birds-eye view, and was viewed as the "Eagle" among the four living creatures (which traditionally symbolize the four Evangelists). The beloved disciple.
"The Jews" are the Jews qua a people among other peoples: the majority of them rejected Jesus as the Messiah. It may also be a way of John (himself a Jew) distancing himself from his race in order to more fully associate with Messians (or Christians in Greek)—people who without respect to race or culture embrace the Anointed of God, who was prophesied to be sought by the Gentiles, and of whom the Gentiles would be made "priests instead of the Levites." John viewed himself a Christian first, and a Jew second. Just as a Catholic might say, "the Catholics at Rome allowed pagan idols to be worshiped," whereas idolatry is a mortal sin according to Catholicism (the First Commandment).
By the point of writing (any time after the Ascension), John (himself a Jew) could safely point to, "the Jews" in general as a people who rejected God in the flesh (Acts 2:36), without implying that every Jew did so (again, Himself a Jew, and the Messiah a Jew), just as one could point to a nation who had more or less given up its Christian heritage as not Christian, despite its remaining faithful adherents to Christianity.