You are beginning to sound like our friend
@Paul the Wolf.
It's not about rejoining the EU it's about finding a way to trade with them from the outside. Yes, it will be more difficult but not impossible, we may
have to become a 'rule taker' not a 'rule maker', then so be it. There are always 'quid pro quo's available.
Again political changes occurring in the EU will make the picture different to what it was. I agree with Paul in that the EU will not (cannot) change it's trading rules on single market and customs union etc. but 'freedom of movement' is going to go, even in the EU. The emergence of exploding migration, some caused by wars, but increasingly in future by climate change, is going to happen and by the end of this century many countries on earth may well will be unable to sustain life, or have disappeared like 'Atlantis', under the waves
The problem in looking back is that politically the further we move away from 2016 and the referendum, more and not less light needs to be shed on what is required to be done
now, facing current dangers. Re-running a flawed referendum from almost 20 years ago, one that should never have been held in the first place, will solve nothing going forward.
Any UK leader spending any time on entertaining this thought, never mind acting upon it, is doomed to failure.
It isn't just that old Brexiteers will have died off, just listen carefully to some of the youngsters you are advocating should vote, many are more aware than most people think. First, it's looking forward they want not looking back, secondly, and admittedly only fairly recently, the rise of far right groups in Europe is just as horrifying to them as Farage and Co are here.
The world is changing it's more volatile and uncertain now than when the Brexit referendum was held, e.g. the long term effects of the Covid pandemic are not just about physical health, it's effects on mind as well as body is longer lasting, maybe much longer than anyone yet realise. The working from home situation that is becoming embedded after Covid has not been a panacea for anything except perhaps curtailing the spread of Covid.
Other pressure beside trade will drive both the EU (as a political entity) and the UK to new horizons, and if we cannot trade amicably with them, there will come a point where they cannot trade with us and both will suffer, much more than they need to. Starmers right changes are afoot and its heads up and looking forward we need.