The 144,000 must be explained from a hermeneutic at 30,000 feet, and not necessarily in this particular instance from a hermeneutic of parsing nouns and verbs in the original languages.
In the Hebrew Bible, the faithful remnant were a subset of Jews. Please click here. That is, while all Israelites were the biological descendants of Abraham, they were not all sons of the Promise by faith like Abraham. That is, there were disobedient Israelites in the Hebrew Bible, and they were therefore not part of the faithful remnant -- the Apostle Paul specifically mentions the faithful remnant of Israel in Romans 9:27.
When Pentecost occurred, the entire faithful remnant of Israel at that time passed from the Old Covenant and into the New Covenant. (According to Matthew 24:6 in partial fulfillment of Ezekiel 37:12-14, some of the faithful remnant who had died actually rose from the dead in order to participate in Pentecost.) The faithful remnant, again, are those Jews whose faith was in the Promised Seed (Jesus Christ), and of course all unbelieving Jews were cut off from the New Covenant. Please click here. Shortly after Pentecost the Gentiles were added (or grafted) into the “olive tree,” which Paul discusses in Romans 11:11-24. I call this olive tree the Tree of Life, because it is through Jesus Christ that eternal life is restored, which had been lost by Adam when he sinned (please see Genesis 3:22-23).
The New Covenant was never given to the Gentiles in the Hebrew Bible, but was an exclusive right and promise to Israel alone. The grafting of the Gentiles into the olive tree (Tree of Life) is only possible through Jesus Christ. That is, at the present time, both Jews and Gentiles are members of the same body because they are supernaturally baptized into the Body of Christ by the Holy Spirit – thus they are one body with Christ, and therefore participate in the New Covenant (1 Cor 12:13).
At a certain point in the future, when apostasy will characterize the professing Body of Christ (1 Tim 4:1-5; 2 Tim 3:1-5; and 1 Thess 2:3), the Gentiles will be broken off (Romans 11:22 and Romans 11:25). What that means is that the time of baptizing believers into the Body of Christ has come to an end. What faithful remnant among Gentiles and Jews on the earth at that time will be removed (1 Thess 4:15-17).
Thus, from that point forward, the New Covenant will be the exclusive prerogative of Israel as was promised in the Hebrew Bible. But there is a problem. There are no believers on the earth, since what faithful remnant remained was taken away. Thus the Lord will call 144,000 Jews (who are biological descendants of Abraham) to be his faithful remnant on earth, and they will be the ones through whose ministry peoples of the earth will be able to participate in the New Covenant. They will be witnesses of the Lamb. The Lamb is the Promised Seed, who like Isaac (the Promised Son to Abraham), was the sacrifice to God. If we compare Gal 3:16 with Gen 22:17-18, then Isaac is the type of Jesus Christ, who is the Promised Seed that is sacrificed to God (in this case for the atonement of the sins of the world).
Please note that these 144,000 are sealed not only because they are God’s chosen ones, but so that they will not be killed by the divine judgments that will follow (see Rev 7:3 and compare with Rev 7:16 for those believers who are not sealed). In Rev 14:1 the mark of the 144,000 is in contradistinction to the mark of the Antichrist in Rev 13:18. Thus the mark (seal) of the Antichrist is his false “New Covenant” written on the heart and mind, and the mark (seal) of the 144,000 is the New Covenant of the Lamb (also written on the heart and mind per Jeremiah 31:33 when compared with Hebrews 8:10)... So the gospel message of the 144,000 will be no different than it is today. The only difference will be that believers will become part of the faithful remnant of Israel and not members of the church (Body of Christ).
Do you remember all those passages in the gospels that spoke of the doom of Jerusalem in AD 70? Those same passages now will apply to these believers (living in Israel) in the future. That is, they will be saved if they persevere (and of course they must reject the false “New Covenant” of the Antichrist and suffer accordingly). Now all those unfulfilled predictive prophecies in the post-exilic prophets (such as Joel, Zechariah, et al.) start to come into focus because now we are talking about “Israel” and the faithful remnant again, which will be purged in the Day of the Lord that starts (in darkness) and will end in light.
After the Second Advent, when Jesus Christ saves the faithful remnant living in Israel, these believers (along with the faithful remnant from the Old Testament) will become members of the Body of Christ at the marriage supper of the Lamb, when all faithful from all ages will be “one flesh” (or married) to the Body of Christ.
Thus the 144,000 are actual biological descendants of Abraham, who will witness to Jews and Gentiles in the end times concerning the Lamb of God. This hermeneutic is normal, and accepts a plain reading of the Scripture. That is, what was predictive prophecy in the Old Testament still remains predictive prophecy in the New Testament.