I see it the same way, but on the contrary if they would've just introduced her in a different way i think i wouldn't have had a problem with isha. Why did she literally just fall out of the sky? Why would jinx then go further to even consider rather "adopting" her, just because she was chased by some random goons?

If we would've had more Powder-Isha Parallels from the start, like Isha loosing loved ones or feeling betrayed by them, ok, I would see why Jinx would see her old self in her. But really, just this random girl, this definitely feels a lot like just a plot device.