My opinion on Japser isnt as strong as my opinion on the Diamonds, But naturally, I believe she too can grow and change. She clearly has been through a lot in her life, which led her on a very aggressive path.
Unlike the Diamonds, her actions arent exactly the result of “ignorance from above”: but more of an expression of deep insecurities and pain she feels within herself. So Jasper, on the surface, seems like your stereotypical bully (check the way she treated Amethyst)- but she isn’t entirely at fault here. She was fed by the HW mentality, and her idols (The Diamonds) reward that sort of attitude.
Jasper is sort of… the HW version of Bismuth. Both have strong beliefs and will act according to those beliefs no matter who stands in the way. I’m convinced that just as Steven was able to make Bismuth somewhat cooperate with his plans to talk to the Diamonds, he’ll manage to talk through to Jasper.
I believe characters like Japser and Bismuth are there to teach us that SU doesnt support the “kill instead of talk” attitude, no matter what side you are on. Theyre here to show us that even people with good intentions, or justifiable motives, can still fall to the wrong path.