Great analysis! Once again I see it differently but it's always cool to hear other perspectives.
I would agree that the protagonist's journey is often a primary part of a good film, but it's far from always the primary part of a good film. To me Evelyn and her arc filled a role closer to Nick(?) in The Great Gatsby, or Will Turner in Pirates of the Caribbean, or whats-his-face (the main guy, not Fred Rogers) from A Beautiful Day in the Neighborhood. They're the focal point of the story and are what drive it forward, but even though they have the most screentime the most interesting thing about them is their interaction with a 'side' character as a foil. While everything you describe regarding Evelyn and trying to support someone you care about are undoubtedly significant parts of the movie, they're not what make the movie stand out to me, and not what I would use to describe the 'point' of it.
Like you said, Joy and Evelyn wrestling with similar issues creates a great dynamic, where each offer different perspectives and challenges to the other. Where it sounds like you found Joy and her role in the movie to be more of a support in the main story of Evelyn's journey, to me Evelyn's side of things was more the lens through which to view the central story of the everything bagel. I see Evelyn's progression as being metaphor for how depression and nihilism creep in. Every part of her journey is another way you keep trying to fight it off, either internally or as help from loved ones, but things keep escalating no matter what you do until you end up at the bagel. The everything bagel's appearance and the Joy/Jobu reveal is the realization of what's been happening. From there it's less about the characters and more just the fundamental fight between the parts of us that can see a way of existing in the world and the parts of us that can't, whether those parts come from within or from loved ones.
To be clear I'm not trying to imply what you wrote is wrong in any way; I just thought it was interesting how, if I was asked to describe the movie's point, I would have given an answer more about the overall story and bagel-adjacent stuff than Evelyn's character arc. Our own experiences with the subject matter of the movie no doubt color our interpretations of what parts seem more 'important' than others. We can both be right :)