Scout
A good question to ask is: How would the Christians in the first century have understood Jesus' words? ..........The early Christians would have understood Jesus words to mean that soon ( in their lifetime ) Jesus would return and reward them with eternal life and destroy their oppressors...... This is the understanding that Paul had, as shown at 1Thess 4:17: "Then WE which are alive and remain shall be caught up together with them and meet the Lord in the air.
But I'm afraid I don't think that's a good question to ask at all. Why on earth would the people of 2,000 years ago have a clearer understanding than the generations who would follow them? Jesus disciples repeatedly failed to understand & missed the point. They were only human, like JWs, catholics & others - not infallible.
Of course the first Christians were millennialist. Clearly Paul was millennialist when he wrote to the Thessalonians (believed to be his earliest letter). Like all millennialists he believed that Christ's return was imminent and there would be terror and destruction, with only a very small group of elect to be saved and taken directly to heaven.
But Paul changed his mind on these things. By probably his last letter, to the Romans, he wrote 'Israel has experienced a hardening in part until the final number of the gentiles has come in. And so all Israel will be saved' (Rom 11:25-26). The imminence of Christ's return was already being reinterpreted within the canon of the NT.
The whole bible resounds with change and reinterpretation, including from OT to NT and within the NT itself. Jesus words "you have heard that it is written.....but I am telling you...", more change.
Of course I would not wish to be stuck with the same understandings of those to whom Jesus addressed his words, and I'm not sure why you suggest their understanding as being so importantl? They all had different pespectives anyway - no one truth but 4 gospels. The fact that they often failed to understand his messages is so clear, but that is admitted within the NT, and so what? I'm not aware of any teaching that suggests 'understanding' is a requirement of salvation - what an anti-Christian teaching that would be.
In Matthew's gospel, in the sermon on the mount, and its preface, the Torah is to be kept in every detail (613 commands) until the end of time. Jesus was a totally orthodox jew and a legalist. But the actual Torah did not remain in force until the end of time, but perhaps it symbolically illustrates the degree of force & commitment to God's law. But what is God's law? The actual 613 rules were abandoned presumably some time after the death of Jesus who had said "the entire law is summed up in a single command - love your neighbour as yourself' Gal 5:14. I believe the apostles that knew Jesus continued to keep the full Torah until they died, so is their way right?
I don't hang on every scriptural word as if it comes from God as if by magic. The bible is not magic, nor do I believe it to be the only inspired scriptures. In fact, outside the JW world, not that many 'believers' believe in magic, ready to be devastated by a so called prophecy that doesn't come true in the way some folks thought it would.