Under Miliband Labour did go for the ´common sense´ approach and got smashed at the polls. The biggest gift to the Tories right now is Brexit and the bounce they are getting from people being utterly fed up of it all. It doesn´t matter who the Labour leader is, they´d still face the same difficulties as Corbyn does today.
Of course it´s a shame for the country but honestly, could you hand on heart say someone like Yvette Cooper would win the next election on a pro remain platform?
No, she couldn't win one - nobody could, it'd take years to reverse the damage in perception.
I think if Labour had been rebranded after 2017 with someone like Starmer, they'd be a shoe-in for an election in normal circumstances (this is a decade of some of the worst Tory governments and PMs in their entire history, alongside austerity), but yes, Brexit is the big difference maker.
That said, it's not an excuse for Corbyn at the one coming up. There's no reason whatsoever why he shouldn't be ahead of the Tories. If he loses, it's because he has no mainstream appeal.
There's a very obvious Momentum bubble where they think "oh, if people don't like Corbyn, why haven't they signed up to be members too and have a voice?" - but they miss the obvious; the 'normal' voter doesn't join political parties. They just vote at elections. And unless I'm very wrong, I think Corbynism has a very, very niche appeal - indeed, you could argue that Brexit has
helped Corbyn, because there's 48% of people who may be tempted to hold their nose and vote for him for the greater good.