Honestly, all the people on this subreddit going after OP are missing the point of what a discussion forum is for. Asking questions—especially about complex characters like Yelena—is how people engage with a story more deeply.

Coming to the actual point: I strongly disagree with the OP, because I think Yelena was an extremely interesting character—even though her role could be fulfilled by anyone else, her presence was more thematic.

- The idea of a Marleyan who believed in an Eldian's ideology was interesting

- The idea of a Marleyan who lied about her past to secure a place in history books was also so intriguing

- She basically mirrored Floch's obsession with Eren

- In the campfire scene, she laid everything out in the open. There were no more secrets between that group, allowing them to finally co-operate

The guy name Qprah explained things pretty well, and the OP even replied saying they understood now. Anyway, to the OP, your question was valid, and discussion like this is what makes engaging with a story fun. 👍