Other nominees for prestigious award include Blossoms, Alt-J and J Hus, and there is room for curveballs such as the Big Moon and Dinosaur

Ed Sheeran, arguably the world’s biggest male pop star, is among the 12 artists nominated for the 2017 Mercury prize, alongside jazz instrumentalists Dinosaur, who, it is fair to say, are on the emerging side of the music scale.

Judges for the prize, established in 1992 as a high-minded alternative to the Brits, announced a shortlist of albums on Thursday that they said “delight in exploring musical possibilities” and refuse “to be be pinned down by genre conventions.”

The list includes two previous winners in the xx (2010) and Alt-J (2012). The 4/1 joint favourites, however, are the grime star Stormzy and the south London singer and producer Sampha.

The outsiders are Dinosaur, four young musicians who met at college seven years ago. Ostensibly jazz performers, they hope they are more than that.

“It’s great to escape the j-word,” said trumpeter Laura Jurd, who composed the songs for the album Together, As One. “Jazz is such a broad word that it can almost be self-defeating … It’s just music. Its trumpet-led instrumental music with a very rhythmic sense and inspired by groove.”

Facebook Twitter Pinterest Alt-J, who won the Mercury prize in 2010. Photograph: Mads Perch

Jurd said they were delighted to be nominated. “To get a phone call and be told we were in the shortlist was a really wonderful, out-of-the-blue surprise.”

Dinosaur’s album is one of the seven debuts on the list. They also include the rapper Loyle Carner, from Croydon, who is nominated for Yesterday’s Gone.

Carner said to be nominated felt incredible. “I’m over the moon, I’m overwhelmed. I can’t really process it at the moment, all I know is my mum’s happy and that means I’m happy.”

Writing the album came easy, he said. “I wasn’t forcing anything, I let it come when it came. For six months I’d write nothing and then I’d write two songs in 3 days. It was sporadic and confusing but enjoyable and rewarding.”

The other debuts on the list are Stormzy, for Gang Signs & Prayer; Sampha, for Process; London guitar band the Big Moon, for Love in the 4th Dimension; Stockport indie band Blossoms, for Blossoms; and the rapper J Hus, for Common Sense.

Many of the shortlisted artists reacted on social media. Stormzy, who is currently touring Australia, tweeted: “I put my heart, my soul and my absolute everything into making this album. Over the moon right now. Giving God the glory.”

If Stormzy were to be named winner of the £25,000 prize, sponsored by Hyundai, it would mean back-to-back wins for British grime following the success of Skepta and his album Konnichiwa last year.

Alt-J said they were “stunned, humbled & ecstatic to be on the list. RELAXER is an odd, mysterious album, we couldn’t be more proud of it.”

Facebook Twitter Pinterest Outliers ... the Big Moon

The other shortlisted artists are the polymath poet and pop star Kate Tempest, who was also nominated in 2014, for her album Let Them Eat Chaos; and the Oxford indie band Glass Animals, for How to be a Human Being.

It is a difficult prize to get right, “like a contest between an orange and a spaceship and a potted plant and a spoon” as Anohni said in 2005 when Antony and the Johnsons won.

Judges are damned if they leave big names out, such as Adele last year, and will likely be damned this year including the multiple Grammy and Brit-winning Sheeran’s all-conquering ÷ album.

Notable omissions were Wiley, Laura Marling, Rag ‘n’ Bone Man and Gorillaz, who memorably withdrew their first album from the shortlist in 2001 because winning would have been “like carrying a dead albatross round your neck for eternity”.

The singer Lianne La Havas, one of this year’s judges, said the list reflected the broad and eclectic nature of British music. She said listening to so many albums showed the UK’s “high quality musicianship” and production skill. “Everything just sounded really good, fundamentally good from the skeleton outwards. I had an amazing time. [Creating the shortlist] was superhard, there were so many albums, but I was surprised at how many I loved … I discovered so much new music.”

The full Mercury prize 2017 shortlist