"Eleven must die in the end so that El/Jane can live" takes just... do not sit right with me and my understanding of El's character arc thus far.
The Lost Sister episode is just an absolute gold mine for insight into El's identity, as we see her leaving the cabin and entering the real world for the first time in search of who she might really be. First we see her try on Jane Ives, the prodigal daughter returned home. She even intends to spend the night in her childhood nursery. She's trying to revive the person she was originally supposed to be by being Jane Ives, who lives with her mom and aunt. But she soon rejects it-- she's not at home here, and runs away again. She isn't Jane Ives. She could have been, if life had been different, but she quickly realizes that it's not a possibility for her anymore.
So then we see her meet Kali, who very much is not Eight. In fact, Kali outright rejects Eight and everything affiliated with her time in the Lab. Here, El tries on just Jane. During her "bitchin'" makeover, Kali literally covers up El's 011 tattoo with a bandana. Kali helps bury Eleven, both literally and figuratively, then asks El to find it in herself, as Jane, to seek revenge and go as far as to not only kill "011," but the men who were behind "creating" 011 and 008.
But, and here's the big insight into who El is, she realizes she doesn't share Kali's mentality at all! She doesn't want to live in anger about her past. She doesn't need to run away from Eleven or the person the lab made her. She doesn't desire to kill the man from the lab, and she runs away for a third time because she realizes that she doesn't want to reject her past or the person her past has made her. She goes home, she returns to her friends and family, she re-embraces El/Eleven.
One of the things that makes El one of my all time favorite characters, is that she doesn't want Eleven to die, and rightfully so! What did Eleven, the little girl fearing for her life in the basement of a lab, ever do to deserve anything other than love and protection? Eleven is a victim that is hurting, and instead of stomping that time in her life into the ground, El carries Eleven into the world. She loves Eleven. Her entire arc thus far revolves around her accepting that Eleven, the girl in the lab, is not a monster and doesn't need to be rejected.
It also doesn't go unnoticed by me that her friends don't exclusively call her El. They still call her Eleven, especially in moments of sincerity and love. Because they love Eleven too. There is no El without Eleven, without Jane, because they're all the same person, which makes her so incredibly, beautifully complex.
El, Jane, and Eleven all deserve a happy ending because every version of her is worthy of love and happiness.
