The First Star is actually evil
So I've been playing Jinx a lot lately, even before the launch or announcement of the Star Guardian skin line. Now that I've played her with the Star Guardian skin, a lot of the quotes wore on me.
"It's my duty to destroy you,"
"First Star made me do it,"
"Sorry nothing personal, I'm obligated to trash you,"
When has Jinx been the character to shift blame of her mayhem to something else? Normally she'd revel in her destruction. Jinx talks about making it 'painless' -- which again is out of character.
My theory is, the First Star is a space conquering entity, like a non visually corrupt Dark Star. What's the least threatening thing? Young girls. Japanese horror also uses young girls because normally they are non threatening. Throw young girls into cute outfits with sparkles of actual death, and you have a combination for a world destroying squad that will seem far from menacing at first.
"Glory to the First Star -- whatever that means," May also imply that Jinx isn't full aware of her actions. She says it with a lot of conviction as if it were her battle cry, but Jinx -- even in the Star Guardian lore is very selfish. She isn't the type to say things she doesn't mean, and she follows her own train of logic. Jinx also doesn't fight for others but herself. Perhaps First Star has some control over the characters? Janna's the mature cool type so she'd be the first to figure it out as seen in series like Yuuki Yuuna and kind of sort of Homura (by chance) in Madoka Magica. Consequently, in the Burn Bright music video -- she's sitting next to the window. This is a trope to indicate the main character of the series.
Jinx also talks about having no idea what was in the Star Guardian contract because it was too long so she didn't read it.
"Pandemonium with a purpose," implies that destruction is the main goal for the star guardians.
My last point is, "First Star says this is all part of the plan!" -- So basically First Star picked a group of girls, and there are rules against destroying shit to mask the controlled and subtle destruction they are inflicting. That's why First Star not only let's Jinx get away with breaking the guardian code and inflicting pain, but also encourages her to destroy more than she herself would like.
tl;dr - My theory is that the First Star is some kind of space entity trying to justify destroying the universe slowly through the use of non menacing girls with morals to fool the public into thinking they're safe while offering a painless end to people around the galaxy/universe.
"I never hurt anyone. It is the performance that kills."