Anony Mous, I think you're thinking along the right lines. We may disagree on the implications, but I agree with you on your initial reasoning regarding the meaning of numbers in Revelation... 😎
If, Jesus says write to 7 congregations, then the number of letters is 7. It is not 8 or 6. In the same way, 7 angels have 7 trumpets and blow 7 times, not 6 times or 8 times.
I consider John*, the author of Revelation, this John is identical to the author of the Gospel. And it is in this Gospel that the writer's "penchant" for different numbers and precise timings is striking. John, for example, lists the 3 festivals of Passover, writes at what exact hour an event took place, counts prices, people, fish...
It's just a hint, it's more of a curiosity, but that interest in numbers, measurements, totals is also found in Revelation. John again is fond of measuring the New Jerusalem, calculating the length of the 1000 years, stating that something was first, and something was second, etc., etc.
So how is it - in my opinion - with the 144,000? Why not 143,999 or 144,001?
I think the number 144,000 is literal because the sum of 12x12,000 is literal. But, there is - in my opinion - a big BUT.
Because in order for any number of 144,000 to come into existence, then in the context of Revelation, the angels will seal those 144,000. This will occur when the Revelation takes place. The question becomes, what about the people who are living in the time before the sealing? JWs-theology addresses this with a sort of excuse that these people are counted in the 144,000 and that there is a sort of "remnant" in the ranks of the JWs. This would assume, of course, that Revelation and sealing is permanent and not from the 6th seal (and lasts until the 6th trumpet). This interpretation, is contrary to their interpretation of 1914... but the contradictions in JWs theology are not important.
How is it then? I think, and the sheer size of the New Jerusalem suggests it, that there will be millions upon millions of these co-rulers and priests with Christ, men and women. Each of those 20 centuries has "produced" plenty of "wheat", sometimes more, sometimes less. Never, as Noah was told, did the sowing and reaping cease. In a symbolic sense, I take it to mean just that in each period, some wheat was born.
In my opinion, then, by the time the last harvest of the last sons and daughters of God begins, then all have the same right and the same chance to be as "last" as the 144,000. And no one can take that right away from them. No theology, no organization. Only Jesus will choose.
I address the question of literal meaning by saying that, yes, it is a literal number, but if there has been no breaking of the 6th seal, then the heavenly government is offered to all who have "an ear to hear". The analogy, then, is with the great multitude at the time of Revelation: these are people who, though they did not know Christ accurately, acted mercifully towards other people. These are the ones who change (literally: 1/3 died after being attacked by 200 myriads of "horses") and show compassion, like the Samaritan. If Revelation were to take place at this time, then the Samaritan represents a merciful Muslim or a merciful Chinese Communist. I deliberately write it this way because I believe in the universality of salvation, which is really based on who is merciful or gentle, and not on the external attributes of "our/foreign"...
*there are various hypotheses as far back as the patristic era on the subject of authorship. The authenticity of God's word doesn't change that in my opinion - see the Letter to the Hebrews, where the author's name is not even directly mentioned.