Nothing in the first chapter of Revelation tells us that the Revelation is limited to the first century. Anyone who has read the Book of Revelation knows that the revelation is a prophecy of the last days and the end if the world. Has that happened yet? NO! We've already gone through your false assumption that the phrase "shortly come to pass" limits the revelation to the first century. Verse 1 of the chapter states:
Revelation 1:1
1 The Revelation of Jesus Christ, which God gave unto him, to shew unto his servants things which must shortly come to pass; and he sent and signified it by his angel unto his servant John:
In God's time frame, what must shortly come to pass could span over thousands of years. Going forward to Revelation 12 we read:
Revelation 12:12
12 Therefore rejoice, ye heavens, and ye that dwell in them. Woe to the inhabiters of the earth and of the sea! for the devil is come down unto you, having great wrath, because he knoweth that he hath but a short time.
Here we read in the same Book of Revelation that John has written that the devil came down from being cast out of heaven having great wrath because he knew that his time on earth would be short. Satan was cast out of heaven before the days of Adam and Eve and was present in the Garden of Eden to tempt Eve. Nearly 6000 years later and he is still upon the earth tempting mankind in that short time he has. That short time spoken of has lasted for nearly 6000 years. So when the Lord shows John things which must shortly come to pass, he is speaking of things in his own outlook or timeframe and not John's which could last several thousand years.
Revelation speaks of the millennial reign of Christ for 1000 years and then the end of the temporal existence of this earth when the heavens and the earth as we know them shall pass away and a new heaven and earth will come where there will be no sea.
Revelation 21:1
1 And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.
Obviously these revelations do not simply pertain to the 1st century and we still have the seas with us today and Christ is yet to reign on this earth for 1000 years.
Its written in the present tense..
and then there's this:
Matt. 24:34 “Truly I say to you, this generation will not pass away until all these things take place.”