You seemed to have answered your own question there; the first resurrection and another after this period of time. That is exactly what I mean by two resurrections. I'll elaborate:
The ones in verse 6 are not judged. They reign with Jesus. That is quite a bit different than those mentioned in verses 12-15 which is clearly different. Also look at verse 5, "the rest of the dead." The first resurrection of the just reign with Jesus during the millennium, the second are raised after the millennium and are judged (v5 & 12-15). Some make it and some don't. All of the ones in the first reign with Jesus and enjoy the promises God made to Jeremiah, Isaiah, Ezekiel, etc.
I don't see anything about a "physical bodily resurrection" in Revelation.
John does write of a physical resurrection in Rev 20. Calling it the "first resurrection." John speaks of the dead in Christ as having lived and reigned with Christ during this time he writes a thousand years. The first group is of those who died as martyrs for Christ. They are living souls in heaven after being killed, faithful unto death they are in heaven the spiritual body of Christ without human form.
Revelation 20:4-6 (KJV) And I saw thrones, and they sat upon them, and judgment was given unto them: and
I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received
his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
Next John tells us the rest of the dead, or those who do had not lived and reigned with Christ within the time symbolized a thousand years. They shall not be resurrected to damnation until this time symbolized a thousand years has finished. That will be in an hour coming, when the last trumpet begins to sound that time (a thousand years) given whereby man must be saved shall be no longer.
"This is the first resurrection" does not belong to the rest of the dead it is written for those saints of vs 6. Those called blessed and holy who have part in the "first resurrection" and have overcome the second death and shall reign with Christ during the same time period as those who were martyred "a thousand years."
5 But the rest of the dead lived not again until the thousand years were finished. This
is the first resurrection.
6 Blessed and holy
is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
This is how we know without a doubt "a thousand years" is not literally one thousand years, but symbolizes TIME given this earth for spiritually building the Kingdom of God in heaven as the Gospel is proclaimed unto all the earth. And because there shall be but ONE bodily resurrection of ALL who are physically dead in the hour coming, when the last trumpet sounds, and time for being saved shall be no longer, we know the first resurrection speaks of the physical resurrection of Christ that man must have part in before they die to overcome the second death.
Vs 4 shows us the martyred saints who had lived and died during this symbolic period of time, and vs 6 shows us that martyred saints will not be the only spiritual body in heaven after physical death. There will also be others who shall also reign with Christ during their lifetime (a thousand years) being part in the first resurrection which is to spiritually have part in the life of Christ through His Spirit in us. When man is born again or born from above, we have part in the first resurrection through Christ, and our life of living and reigning with Him forever begins and death no longer has any power over us. Whether we are martyred for our faith in Christ, or we live and die of old age, as long as we are faithful unto death during time symbolized a thousand years, we shall always be spiritually alive with Christ forever.
The rest of the dead, or those who never live and reign with Christ during their time on this earth are all the dead "small and great" who shall be called to stand before God at the GWT to give account according to what is written in the books and the book of life. Their fate shall be with Satan in the lake of fire that is the second death.