The WTS teaches that the 144,000 of Rev 7:4 is to be taken literally. If chapter 7 of Revelation is to be taken literally, where then does the Bible say that the 144,000 will come from? See Rev 7: 5-8.
Revelation 5:9-10 states: "And they sing a new song, saying: “You are worthy to take the scroll and open its seals, because you were slaughtered and with your blood you bought persons for God out of every tribe and tongue and people and nation, and you made them to be a kingdom and priests to our God, and they are to rule as kings over the earth.”
So, those who are to become rulers in the kingdom of God are taken from all nations and peoples. Revelation 7:5-8, however, presents the rulers of the kingdom as coming from the 12 tribes of Israel. This, though, is not to be understood as physical Israel. Those who are literate in the Scriptures know that Christianity long ago replaced Israel as God's nation. In fact, Jesus pointedly told the Jews that the kingdom of God was being taken from them and given to a nation producing its fruit. That "nation" is what Paul called "the Israel of God" - the Christian congregation. It is from that congregation that 144,000 are taken.