One afternoon last year, Thelma Plum got a text. It was from the producer David Kahne, who was in the studio in New York where the pair were working on her debut album, and it said, “You’ll never guess what happened.”

Another artist in the studio had wandered past, overheard Plum’s Paul Kelly-featuring song Made For You, and asked if he could “lay something down”, explaining: “I’ve got this part that I can hear.”

It would be a bit of an overstep unless you were, say, a Beatle. So that’s how a song that was already a career bucket-list item for a Paul Kelly superfan also scored a guest appearance by Paul McCartney on guitar.

“I definitely didn’t guess that,” Plum deadpans, eyes wide. “It’s this beautiful, simple guitar line. It was so perfect for the song. And also, just how cool – I can probably die now because the two Pauls have been a part of this song.”

For fans who have been following Plum since she was barely out of high school, the album, titled Better in Blak – a collection of plainspoken, sparkling pop songs and naked acoustic ballads – has been a long time coming. The Pauls are just a nice bonus.

A Gamilaraay woman, Plum grew up between Brisbane and her grandparents’ farm 20km outside the New South Wales town of Delungra, and she’s essentially been a working musician since leaving school. The first song she ever recorded – “the first one I really took seriously” – was Father Said, a haunting, assured minute-fifty that she uploaded to Triple J’s Unearthed platform in 2012. It won her the title of the best unsigned Indigenous artist in the country, and a spot performing at the National Indigenous Music Awards, and “it all started from there”.

I can probably die now because the two Pauls have been a part of this song.

“I’d finished school and I was just playing lots of gigs – as many as I could around Brisbane in cafes and bars. I didn’t really have any desire to go to uni, or anything like that. I just wanted to play music in front of people.”

Kelly was “the first white person I’d ever heard sing about Aboriginal people”, she says – but she was also a fan of the few Indigenous women she saw on Video Hits, thrilling to Shakaya and Jessica Mauboy between Madonna and Pink.

Thelma Plum, a Gamilaraay woman, says she grew up ‘not seeing anyone that looks like me’ on TV or in magazines. Photograph: Jessica Hromas/The Guardian

“When I sing [album track] Homecoming Queen, I talk about how I felt looking in magazines and not seeing anyone that looks like me,” she says. “I loved watching television and watching film clips. I didn’t understand and it took me a little bit longer to figure out how to love myself. That I am just as worthy.”

She didn’t – or couldn’t – rush her first album, either.

“I just don’t think I was ready [after her 2015 EP Monsters]. I just think I needed to go through what I’ve been through, my life experiences in the last couple of years, to be able to come up with these songs.”

The starkest example might be the album’s title track, Better in Blak. When she released it as a single in April, she posted on Instagram about its origins: she’d been in the studio in London in May 2018, when her phone began “blowing up” with dozens of messages and comments, mostly containing abuse and slurs both racist and misogynist.

It was an ugly second wind of an old battle back home, sparked in 2016 by a private Facebook post from her about an alleged altercation in a Sydney pub with a member of another band. Screenshots of that post were picked up by local music press, and she became a flashpoint for fans furious at the dent in the band’s reputation.

Now another public post, not from her, reignited the fight, and sent a further chorus of voices to her social media channels – and some of the band’s angry fans to her shows, which she says has led her to sometimes feel unsafe.

It took me a little bit longer to figure out how to love myself. That I am just as worthy.

“When I get messages saying ‘you Abo’ and things like that. I don’t see my friends, my white friends, getting messages that say stuff like that and are that horrific,” she points out. “You can’t say it’s not about colour when they’re the messages that I’m receiving.”

The next day, Alex Burnett, Plum’s writing partner and producer, pushed her to channel it into a driving, sly, phenomenally catchy celebration of her own self-image: “If I knew what I know then maybe I would take it back / but fuck that / I look better in blak”.

“It was really rough,” she says matter-of-factly. “It was really, really sad. I wanted to just delete all of my social media and become invisible to everyone. It was pretty hard and shitty. But then, this song kind of came from that. Sometimes bad things can open a space to create something that’s not bad.”

Plum is a refreshingly straightforward lyricist. The songs on Better in Blak are direct, raw, and often funny: from Do You Ever Get So Sad You Can’t Breathe and Love & War (written with Gang of Youths’ David Le’aupepe as a response to the Don Dale scandal) to the scathing Woke Blokes and the reworked teen angst of the song Nick Cave, a track Plum wrote years ago after a twisted-up teenage heartbreak that led her to pretend that she, like him, was a vegan – when she was extremely not.

“One time we were out at an event and someone came around with antipastos and I, literally, out loud said, ‘Fuck yeah, prosciutto’,” she explains. “He was like ‘Thelma, that’s meat,’ and I was like –” [adopting a look of horrified confusion] “‘What? What do you mean?’ And then I threw it across the room.”

If there’s a connecting thread through the songs, it’s that you don’t need to reject the various people you used to be on your way to loving who you are now; that the ugliness, whether it’s social injustice or trolls or crushing heartbreak, can create beauty and growth if you pick them up and use them as tools, and then moving past them.

“Like this morning, I got a ‘Go fuck yourself’ [on Instagram]. All the time it happens. Like every single day of my life. But I don’t care about it like I used to now. I just want to get on with life and play music. That’s what I love doing.”

• Better in Blak by Thelma Plum is out on Friday 12 July through Warner Music. She is touring Australia through August