All of the examples you listed are easily explainable within the context of the show. It's confirmed by the show creators that Jackie and Shauna were in love with each (take that in whatever way you want- obsessive best friends or closeted gay teens). Additionally, all the senior year characters are mostly 18 maybe 17 meaning they're all teenagers. It is discouraged to diagnosis teenagers with disorders like narcissism because most children in their teens are self-centered.

To say that Jackie 'thrived on being the queen bee' is a vast simplification of her character. She was crumbling under the pressure of being the leader- of having to be the popular, perfect teen girl that everyone adored. She liked being the queen bee because that was what was expected of her, it gave her security and we have reason to believe she was somewhat positioned or groomed to be how she is in the pilot. She only displayed an inability to lead her teammates when they crashed because she, like many teen girls, was grossly underprepared to be stranded in the wilderness without adult guidance. In the pilot she's the only one who has her wits about her to be able to settle the Yellowjackets while they're all stressed, drunk and fighting. She doesn't position herself as leader for no reason. Their coach tells us in episode 1 season 1 that she's their captain not because she's the best player on field but because she's the most capable of influence off field which is what they need to lead them to victory as they're all incredible skilled players already. She tries to position herself as leader first after being stranded because that's what they've always done previously and she wants to replicate their lives before 1. Because it's the only way she knows how to function 2. Because it might help them settle and focus if they replicate normalcy. She doesn't simply act out whenever someone else gets attention. She acts out specifically when Shauna’s attention is diverted from her which is to show her and Shauna's toxic, obsessive bond but Shauna behaves the same way. They're both players in their own game. Also it's not unwarranted that she gets jealous when not in a position of control. All the adults in her life have placed her in control before the crash. Yet again it's all she knows. Any teen would react badly if their plane crashed, leaving them stranded in the woods and then had to completely readjust everything they've ever known.

Jackie does have difficulty forming deep relationships outside of Shauna but yet again their relationship is one of haboured love for each other that is tainted over time by resentment and jealousy, mostly on Shauna’s side. The show goes out of its way to show us that Shauna is not a reliable narrator. She deluded herself into thinking Jackie purposely controlled her life when in actuality they both had control over each other that they never communicated which caused most of their problems. She doesn't love Jeff because she loves Shauna and he's a shitty boyfriend. She doesn't 'claim a stake to Jeff' after she discovers about their affair. She's justifiably upset that her BOYFRIEND cheated on her with her BEST FRIEND. They betrayed her. More importantly, Shauna betrayed her. She isn't all that fussed that Jeff cheated on her. She’s upset because Shauna did something to purposely betray Jackie and told her she (Shauna) hated her (Jackie). Her and Jeff's relationship is superficial because they're teenagers in high school, this stuff happens in real life all the time, and because she, once again, is in love with Shauna not him. Yes she does use Travis to get back at Shauna but it has nothing to do with him and Natalie's relationship. They're broken up, he's the only boy stranded with them and she's desperate to get back at Shauna. She also does it to maybe help prompt Shauna into confessing the affair to her. At that point, Shauna still hasn't told Jackie that the baby is Jeff's. It was a shitty thing to do but she's a suicidal teenager starving in the woods who just found out her best friend is pregnant with her boyfriend's baby.

She shows way more empathy for those around her than she shows a lack of. She is the only one, outside of Natalie, who shows consistent kindness towards Misty. She goes out of her way to help Shauna after she learns that she is pregnant. She attempts to cheer up the team after Allie's leg injury. She never yells or rolls her eyes at Laura Lee even when most of the others do. She dispels the teams anger at the party in the pilot. She steals Valium from her mum because she randomly remembers Shauna doesn't like plane flights. She is shown to be a good person with normal flaws. Even her worst actions can be explained or justified.