Returning, anyway, to the main topic -- rather than repeating previous debates that will just go round in circles -- the fact is that most Remain supporters in Labour are well aware that Corbyn is not very pro-Brexit, but are probably hopeful that he will pivot at the last minute once all other options are exhausted.
At the moment, this doesn't look very likely, and that is frankly a travesty. Remain supporters are numerous, and far from "anti-democratic", but they have not really got a realistic party to turn to to represent them. Why vote for the Tories, the very party from whom this mess originated? Why vote for Lib Dem? Unless people switch there in droves, and probably not even then, this would simply leave the Tories with an even greater grip on power by splitting the Remain/non-Tory vote?
And why vote for Labour, whose leader is clearly out of touch with his party at precisely the moment when he should be at his strongest?
It's a mess, and, frankly, Remain supporters are far more aware of it than you are. And yet the irony is that you'd probably have found Brexit delivered far more effectively if Corbyn were in charge to start with. At least he believes in it, unlike Theresa May -- even if he has not the guts to say so, or the sense to abandon this position or step aside in favour of one who will.