For the record, I would like to assure the saints that I believe that Christ's second coming is future from now.
However, Christ Jesus our Lord commanded John the Revelator to write what he saw (and heard, etc.) and send it to seven Asian Churches of the first century.
So, if the text of what John wrote to the 7 Asian Churches did not have meaning for their first-century time frame, then there is no real point to the book of Revelation in general.
There is indeed a reason for the "first resurrection"--and that reason has to do with the reality that the saints in this verse (in bold below):
8“I am the Alpha and the Omega,” says the Lord God, “who is and who was and who is to come, the Almighty.”
9I, John, your brother and fellow partaker in the tribulation and kingdom and perseverance which are in Jesus, was on the island called Patmos because of the word of God