It is easy to forget that, on arrival in 2000, Gorillaz looked suspiciously like a self-indulgent novelty turn, the kind of project record labels feel impelled to let rock stars do when they’ve shifted so much product that “no” isn’t really an option any more.

It was a Britpop frontman and his artist flatmate’s sneery joke at the expense of manufactured pop, with cartoon figures replacing the hapless, manipulated band members and interviews conducted, a little wearyingly, in character. You would have got pretty long odds on it still existing 17 years on, longer odds still on their fifth album being a politically charged conceptual work that variously touches on the topics of racism (courtesy of rapper Vince Staples on apocalyptic choir-assisted opener Ascension), mental illness, the pernicious influence of the internet “echo chamber”, western military intervention in the Middle East, the “alt-right” belief that China has fabricated global warming, and the importance of soul music in the Thatcherite heartlands of 80s Essex (the improbable latter topic surfaces on a lovely track called Andromeda, named after a defunct Colchester nightclub, which also finds Albarn ruminating on the deaths of both his partner’s mother and Bobby Womack over a four-to-the-floor house beat and frail electronics).

And you would have been laughed out of the bookies had you suggested that it might feature among its stellar cast Noel Gallagher, a man keen to offer interviewers his considered critical appraisal both of Gorillaz’s eponymous debut (“appalling – music for fucking 12-year-olds”) and its mastermind, Damon Albarn (“That cunt is like, ‘Is there a bandwagon passing? Park it outside my house.’”) And yet, there he is, on Humanz’s rousing closing track, the unlikeliness of the situation compounded further by the fact that he’s singing: “We’ve got the power to be loving each other no matter what happens” in unison with his former nemesis.

But as Albarn would concede that things don’t always turn out as you expect. He is, after all, currently promoting a Gorillaz album whose concept was based around conjuring up the dystopia that might ensue if Donald Trump became US president. This was a notion that seemed so ridiculous and inconceivable it caused widespread hilarity in the studio when he announced it. Rather than a knowing joke, Gorillaz turned out to be the smartest artistic move of Albarn’s career, emancipating him from the Britpop millstone, revealing him not as a bandwagon jumper, but as the one inarguable musical polymath that maligned era produced. It is possible that he might have gone on to work in Afrobeat and Syrian orchestral music and write operas based on Chinese folk music had Gorillaz not been a vast transatlantic success, but it’s certainly harder to imagine.

Humanz demonstrates the pros and cons of Albarn’s musical restlessness. As usual, he displays exquisite taste in collaborators – everyone from fast-rising rapper DRAM to dancehall singer Popcaan to old-school Chicago house legend Jamie Principle – and an impressive ability to get the best out of them by throwing them into unlikely circumstances. It’s tempting to suggest that Submission is precisely the kind of out-and-out pop song that alt-R&B vocalist Kelela’s career has thus far lacked. Grace Jones sounds particularly magnificent improvising a vocal around a post-punk-y distorted guitar line, with Albarn singing in blank-eyed cockney Syd Barrett mode on Charger, while the conjunction of De La Soul, a relentless distorted techno beat and synthesiser, courtesy of Jean-Michel Jarre, on Momentz is dazzling.

On the downside, it seems a little light on hooks, as if the business of experimenting with production and the excitement of juxtaposing incongruous musical bedfellows took precedence over writing hits. It is a shame, because when Albarn remembers to come up with melodies, his trademark languid melancholy is as affecting as ever: Hallelujah Money and Sex Murder Party offer particularly haunting examples. In addition, Humanz can feel a bit like a scattershot collection of tracks, rather than a coherent album. It is a state of affairs compounded by the fact that, as is usual with concept albums, the concept doesn’t always hold up over the full 49 minutes. Some tracks fit the party-album-for-a-world-gone-mad concept, others are patently off-topic – and the spoken-word interludes, which reference everything from the Clash’s London Calling album to the old crowd shouting “Yes – we are all individuals!” joke from Monty Python’s Life of Brian, don’t make a vast amount of sense.

Then again, you could argue that is less a failing than evidence of Albarn’s ability to move with the times. After all, we live in an era where the world’s biggest stars refer to their new releases as playlists, rather than albums. And the one thing Humanz never does is suggest a decline in inspiration on the part of the man behind it. Quite the opposite: the ideas are still coming in such abundance, it seems to occasionally prove a struggle to marshal them. There are substantially worse problems for an artist to have than that.