I can't believe anyone could write so much and yet say so little.
In some respects you have a point that if you want to win you have to reflect what the electorate want. Maybe if Labour were massively behind in the polls and they had to try and gain some credibility you'd have a point but you are completely wrong with where you think Labour can be successful in the current climate. The Tories are currently unelectable to the point anyone could beat them. There is no need to become a right wing party just to win at the moment because there is no opposition.
All of that is irrelevant though. I can't fathom how anyone could have such faith that Starmer will deliver what you want him to deliver in the short or long term. He is not brave enough to tell us what he believes in and he's changed his mind on everything he's ever said so I have no idea how you can have any belief that he will win and then move to where you want him to when the likelihood from the evidence he's so far provided is he will move wherever he thinks he can find more votes and that is more likely to be further right than left.
In a 2 party system if you can base yourself on the opposite side then the opposition has fewer potential voters. That means that he is more likely to move towards the right to win votes which pushes everyone further right. That is an incredibly dangerous situation for normal working people to be in. How you can have the gall to claim that I or other left wing voters are Tory enablers is astounding. You are not only going to vote for a left wing party to move to the right but you're even championing it as the right thing to do.
I don't believe you are stupid but your arguments for that position are idiotic.
You can ignore the numbers all you want, just like Corbyn did, ignorance might be bliss to you, but for those in the real world, it certainly isn't.
Labour were behind in the polls because the previous guy lost twice, and was luke warm on remain, which helped the leave and far right uprising. You can't use the reason we've got the polls back, as a reason to go back to the way they were crap to start with, that makes zero sense, and would probably mean a much lesser win, no majority, or losing a second term which is going to be critical. The second term is going to be just as important as the first.
The tories are unlectable, now, from what the previous idiots did, but it will likely be closer come election time, in the same way that remain assumed they would walk the brexit vote. The Tories were poor, and proven poor, when Corbyn took over, got worse by the time he had his first election and were the worst I've seen by the time of the second, yet he still didn't win, and Labour didn't get any of their 3 targets. Labour didn't even get close on seat numbers and then got battered in the second attempt. A loss isn't second place, it might as well be last place, as you get little say, and zero actions.
I've got faith in Starmer as he understands the tactics and maths of it at least, and without that you've got nothing. As a party they will come up with a manifesto which will be electable against the tories, and likely massively differ from the Tories. If it doesn't I'll say you're right, but it won't be happening. Some aspects may be similar in each of their manifesto's, but that's unavoidable, in some areas Labour and Tories do want similar things, or at least in the Tory case they say they do, where as Labour actually do. Two parties can enact the same policy very differently.
You had (and somehow still have) faith in Corbyn, who lost two elections and who was "running" the supposed red wall when loads of them voted leave, and you still want to go back to that, it's madness, it's proven not to work.
You don't have faith in Starmer as he's not Corbyn, and because of 10 pledges which became outdated in about 10 minutes, this isn't his fault, things changed, a bigger problem is your tunnel vision and lack of reality.
Starmer doesn't need more votes, he's got plenty, and as time moves closer election confidence will increase, and thus they can narrow down their vision. Sunak will probably hoover up some of the votes which Starmer currently has, and it won't be the left ones, so Labour will probably win with less voters on the right side of Labour now (the political centre). Labour will then probably set their manifesto on centre left, to suit the core of their vote, and retain those swing voters who are crucial to actually winning.
You don't have any evidence that Starmer will put in less left or centre left Policies than Corbyn, actually, it's a certainty that Starmer can't put in less, as Corbyn was proven to enable zero. There's no Labour or Tory manifesto and Labour have not won yet, never mind had 5 years to change anything. The only evidence we have is that Corbyn lost twice and was running the "red wall" when a lot of the red wall voted out. By the time of the election that will be 10 years of Tories since Corbyn took over in 2015. Sure, two of those years he was in opposition because of Millibands loss, but Starmers having to pick up the pieces of 5 years due to Corbyns last loss.
The two-party system you mention only exists if there's right and left only, but the comment you make on that helps me understand where you're failing to understand now. It doesn't work if there's left, centre left, centre, centre right and right people, with left or right choices only. The country is weighted with a heavily central bias, that probably leans right through media influence. Tories get in power more times as they hoover up these centre voters (by Tories and the press lying to them), they're swing voters and their vote is worth more equity-wise.
I think I know what you're getting at, by only giving up enough ground to still win, but there's extreme risk on that, and this appears to be your second choice. Your first choice was seemingly Corbyn, and he didn't what you're seemingly proposing now. He tried to move people left I suppose, but he didn't succeed at doing it, and it allowed the UK to move way further right. Had he targeted the centre or been a better leader then he may have been able to win, but he didn't do either.
