The musician, who identifies as non-binary and uses they/them pronouns, said they didn't think they were "Brits material" but were "really glad" the critics believed they were.
Jacob built a reputation in Edinburgh's folk scene after a difficult stint at university and a turbulent period in London.
The storytelling quality of the genre influenced debut album In Limerence, which discusses failed romantic relationships.
Jacob thanked those who had recognised their work, saying: "When I started making this album, when I write songs, it's so far away from any of this stuff and I never would have expected it to get this far.
"It feels like I'm getting away with something that I shouldn't be getting away with.
"So thanks for making me feel cheeky and very, very proud."