Revelation 1.4-5 : “From John to the seven churches… may grace and peace be given to you from him who is, who was and who is to come, from the who are before his throne, and from Jesus Christ…”
Who is writing?
John is indeed the human author: he writes the letter, signs his name, and addresses the churches directly.
But he presents himself as a messenger: he passes on a revelation that does not come from him.
That is why he says: “from…” → he places himself as a relay, not as a source.
The three “froms”
From God: “him who is, who was and who is to come” → the God, present throughout all time.
From the : a symbolic image of the fullness of the Spirit of God (the number 7 = totality). This means that the Spirit acts in fullness before the throne.
From Jesus Christ: presented as the faithful witness, the first to rise from the dead, the ruler of kings.
These three “froms” form a Trinitarian greeting: God, the Spirit, and Jesus Christ. John writes, but he places his message in this divine source.
In summary
Yes, it is John who writes.
But he insists: the content comes from God, through the Spirit, and through Jesus Christ.
His formula “from…” is a way of saying: I am writing to you, but this is not my message; it is the one I received and that I pass on.
This gives Revelation its authority: it is not a personal opinion of John, but a revelation that he faithfully relays.