“And I saw another angel ascending from the east, having the seal of the living God: and he cried with a loud voice to the four angels, to whom it was given to hurt the earth and the sea, Saying, Hurt not the earth, neither the sea, nor the trees, till we have sealed the servants of our God in their foreheads. And I heard the number of them which were sealed: and there were sealed an HUNDRED AND FORTY and FOUR THOUSAND of all the TRIBES OF THE CHILDREN OF ISRAEL. –Revelation 7:2‭-‬4 KJV

This group of 144,000 appear to be ALL the genuine children/natural descendants of Israel scattered abroad across the earth.

The next group of 144,000 appear to represent ALL OF THE FOLLOWERS OF JESUS on earth at that time, as distinguished from the unbelievers:

“And it was commanded them that they should not hurt the grass of the earth, neither any green thing, neither any tree; but only those men which have not the seal of God in their foreheads. –Revelation 9:4 KJV

THE SEALS AND MARK ARE NOT ARBITRARY they distinguish between God’s children and Satan’s:

“And the rest of the men which were not killed by these plagues yet repented not of the works of their hands, that they should not worship devils, and idols of gold, and silver, and brass, and stone, and of wood: which neither can see, nor hear, nor walk: Neither repented they of their murders, nor of their sorceries, nor of their fornication, nor of their thefts.–Revelation 9:20‭-‬21 KJV

“And I looked, and, lo, a Lamb stood on the mount Sion, and with him an hundred forty and four thousand [saints in heaven], having his Father’s name written in their foreheads. And they sung as it were a new song before the throne, and before the four beasts, and the elders: and no man could learn that song but the hundred and forty and four thousand, which were redeemed from the earth. These are they which were not defiled with women; for they are virgins [spiritually faithful to God]. These are they which follow the Lamb whithersoever he goeth. These were redeemed from among men , being the firstfruits [the harvest of souls] unto God and to the Lamb. And in their mouth was found no guile: for they are without fault before the throne of God…. And the smoke of their torment ascendeth up for ever and ever: and they have no rest day nor night, who worship the beast and his image, and whosoever receiveth the mark of his name. Here is the patience of the saints: here are they that keep the commandments of God, and the faith of Jesus. –Revelation 14:1‭, ‬3‭-‬5‭, ‬11‭-‬12 KJV