I think regardless of whether or not you're a Jaune stan (and regardless of your opinion on Jaune at all, for that matter), you're 100% right about Jaune's introduction being an important scene.
By this point, the four title characters had been introduced and their personalities had been established. So, we're all set in regards to them. With the title characters all squared away, now is the perfect time to introduce some significant supporting characters, namely Team JNPR.
It's absolutely important for the main characters to have relationships with people outside of their own group. Otherwise, it feels like they're trapped in a little box together. That being said, Jaune's introduction was nicely done, because literally right before, Ruby had a bad first impression with Weiss and Blake, after having been ditched by Yang.
Mind you, Yang wasn't being malicious. She just wanted Ruby to learn how to branch out. Ruby had already disregarded to need to make friends, so long as she could tag along with her big sister, prompting Yang to give her the extra push. Ruby then having a bad encounter with Weiss and being brushed off by Blake (even if Blake did defend her from Weiss) definitely didn't help her anxiety about meeting people. But then along came this awkward dude, and gave us hope that Ruby would be making friends after all.
I also like that Jaune is Ruby's first friend at Beacon Academy. I knew the main girls would end up being tight-knit eventually. Seeing them get off to a bad start and have no interest in bonding would make their eventual friendship all the more satisfying. That's why it just kind of works this way by having Ruby befriend someone else first. That way she's not all sad and alone during the rough start. Also, it opened the door for us to meet other important characters like Pyrrha, Ren, and Nora (AKA, the best girl).
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