The 24 elders are most likely a hierarchy of angels.
They are elders, not angels.
There is nothing that suggests the 144,000 are raptured.
I don't believe that you understand what first fruits are. First fruits are harvested first and presented to the priest, or in this case Jesus. They are before the throne of God and are redeemed from the earth.
Rev 14
3 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.
4 These are they which were not defiled with women; for they are virgins. These are they which follow the Lamb whithersoever he goeth. These were redeemed from among men,
being the firstfruits unto God and to the Lamb.
It doesn't imply the 144,000 sing the song of Moses.
Correct. It does not imply that the 144,000 are singing the song of Moses. The 144,000 are singing a new song before the throne and no man can learn the song but the 144,000 that are redeemed from the earth.
Rev 14
3 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.
Those that are singing the song of Moses, sing this song before throne in THE MAIN HARVEST. The 144,000 are first fruits of this harvest. Here is the main harvest........which is the second harvest.
Rev 14
14 And I looked, and behold a white cloud, and upon the cloud one sat like unto the Son of man, having on his head a golden crown, and in his hand a sharp sickle.
15 And another angel came out of the temple, crying with a loud voice to him that sat on the cloud, Thrust in thy sickle, and reap: for the time is come for thee to reap; for the harvest of the earth is ripe.
16 And he that sat on the cloud thrust in his sickle on the earth; and the earth was reaped.
Here is another view of this harvest. Again, this is the second harvest and it occurs at the 6th seal.
Matthew 24
30 And then shall appear the sign of the Son of man in heaven: and then shall all the tribes of the earth mourn, and they shall see the Son of man coming in the clouds of heaven with power and great glory.
31 And he shall send his angels with a great sound of a trumpet, and they shall gather together his elect from the four winds, from one end of heaven to the other.
That would be the 5th seal martyrs according to the description given in Rev. 15.
The 5th seal martyrs are going to be mostly Jews. The Church will already be in heaven before any seals are opened. The 70th week of Daniel is about the people of Daniel. Contrary to popular belief there is only 3.5 years left in the 70th week of Daniel.
So the final week will begin when a 7-year covenant with many is made. The Church will not be raptured before the week begins as Noah was not in the ark 7 days before the flood. The day of the seven, Noah was loading the animals and we don't know what day Noah was sealed in the ark. When the Church is raptured, the fullness of the Gentiles will be come in. Then blindness will be removed from part of Israel.
Romans 11
25 For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in.
The great tribulation is about the Jews. Any Gentile raptured during the great tribulation will be the poor and the stranger, meaning they have not heard the Gospel prior to the tribulation.