The first leaders’ debate saw the prime minister, Boris Johnson, pitted against Labour challenger Jeremy Corbyn in a fractious contest with few surprises and no upsets.

Corbyn, as expected, showed his more nimble skills in the political cut-and-thrust against the lumbering and sluggish Johnson, who stuck so rigidly to his pre-prepared Brexit line that the audience was audibly groaning by the end. Have I Got News For You must seem like a distant memory for the increasingly dislikeable PM, whilst a fair referee would have granted Corbyn a narrow victory on points. But what can the rest of us take away from this heavily-promoted political slugfest?

1. Jeremy Corbyn is at his best unscripted.

Perhaps Corbyn’s best single answer came at the end of the show, with each opponent asked what they would buy the other for Christmas. These things are a nightmare to prepare for; there’s no way to know what to expect, and no way to give a right answer – but Corbyn seized the moment, and showed a nice touch of humour, offering Johnson a copy of Charles Dickens’ A Christmas Carol, to audience laughter.

2. Johnson doesn’t do human.

Johnson, by contrast, fluffed his answer to the same question – his switch back to the script, promising Corbyn a copy of his Brexit deal to read, could have been a brief moment of self-awareness, but so clearly wasn’t. His flapping a few days earlier, when asked how he could be ‘relatable’ for most people, given his toff background – a question, incidentally, the even toffier David Cameron smoothly batted away – was of a piece. Note also his bafflement when confronted on the campaign trail. It’s quite striking how bad he is at this.

3. Brexit is wearing thin.

Johnson knows his audience: keep talking Brexit, get the base out. With the Brexit party torched by Nigel Farage, this is the Tories’ biggest selling point. Trouble is, it is close to their only selling point. Unlike Theresa May’s ‘Strong and Stable’, Johnson’s ‘Get Brexit Done’ at least has some content – but spending five weeks banging on about something most of the country are heartily sick of may not be quite the genius campaign strategy it first appears to be.

4. Labour’s Brexit plan can withstand scrutiny.

Labour’s position on Brexit – renegotiate deal, put to people in referendum, implement result – is focused on process, rather than outcomes, as one of the few plausible routes to seriously resolving the unholy mess that is Britain’s attempted exit from the European Union. But by necessity it doesn’t have the single sentence simplicity of ‘Get Brexit done’ or just ‘Stop Brexit’, something the proponents of both options have zeroed in on. Johnson repeatedly returned to the question of Labour’s Brexit position, challenging Corbyn to state his own preference in a hypothetical second referendum – but he failed to find the means to crack the policy open, Corbyn sticking to the script with discipline. Likewise on the purported deal with the SNP, which Corbyn could give a very clear, robust answer to.

5. Outside of Brexit, the Tory campaign is relentlessly, mindlessly negative.

After nine years of visible and consistent failure in office – stagnant living standards, crumbling public services, even Brexit remaining undelivered – the Conservatives can’t defend their own record and have few places to go other than focusing in on their Labour opponents. But far from the sunny optimism Johnson is supposed to be known for, both his opening and closing remarks focused relentlessly on attacking Labour and Jeremy Corbyn. Some handwaving about police and some lies about hospitals can’t disguise the ugly nihilism at the centre of the Tory offer.

6. Even the Tories’ own attack lines seem to be fading away.

Just over a week ago, the Tory press were blaring news of the utterly fake £1.2tn price tag attached to Labour spending plans, based on a manifesto that hasn’t even been published yet. At the end of last week, we were given similarly ludicrous made-up figures for the number of migrants Labour’s alleged migration policy would lead to. Both seem to have been forgotten again this week; an indication of just how seriously even the Tories took them, but also of an underlying weakness in their campaign – they can’t stick to a line on the economy, because what they have is threadbare. Labour must exploit this.

7. Labour has found some serious weakspots in their opponents, but must point to a better future.

Corbyn’s other best moment of the night was entirely scripted – a smart and theatrical waving of the notes from a secret meeting between Conservative government officials and US trade representatives to discuss the NHS. The very real risks to the NHS from the Tory Brexit deal have been highlighted over and over again by Labour – as they should, since it is all-too-obvious that carving up our previously protected health markets for the benefit of US corporations is the biggest single prize the UK can offer in any future trade deal.

But for Labour this can’t be enough: it needs to say how the future will be different, and better. It’s essential that Labour owns the future, in contrast to the Tories’ miserable present. The full-fibre broadband announcement was a brilliant version of that – a single policy that encapsulated a radical, universal offer and a vision of different, better country. More should be made of this and those visionary parts of the Labour programme.

8. Empathy is wasted on Boris Johnson.

We know, by now, that Jeremy Corbyn is a decent human being who genuinely cares about people and that, if he says he wants to bring people together, he means it. But in a straight fight against a brutal opponent, he will also need to show some teeth. If Johnson and the Tories want to polarise this election on Brexit lines, Labour needs to offer an alternative polarisation – the many versus the few, the people versus the elite. That means drawing out the points of opposition and returning, again and again, to what the Conservative leadership stands for: the few, not the many, from their billionaire backers to their plans to carve up the NHS. Associate Trump, arriving in the UK shortly, with Johnson. Make Labour’s vision of the future credible by showing today how the wealthy oppose it. Draw the lines and name some enemies.

Perhaps the most telling moment of the night, however, didn’t come from either of the two contestants. It was when Corbyn made the unarguable point that climate change would affect the world’s poorest, but the jeering and audible heckling in response from a small section of the audience was chilling. The Tories have – deliberately and cynically – stirred up the very worst parts of British society, and those jeers were a brief glimpse into it. If Johnson wins, these will be the people walking taller on the morning of 13 December, and they will soon have their victims. The next three weeks matter.

James Meadway is a Novara Media columnist and former advisor to the shadow chancellor, John McDonnell.