Spiritual person here. I can only give you my perspective, so grain of salt and all that.

I classify things in four categories, physical, mental, emotional, and spiritual health.

• Physical is self explanatory I think.
• Mental is about structure of the brain and touches on things like ASD, ADHD, bipolar, and schizophrenia. It’s about things that are related more to the way the brain is functioning rather than environmental factors (please don’t think I’m equating ASD to mental disorders, it’s about how the brain is working more than the thing itself)
• Emotional is about how a person feels, moods and such. This touches on situational depression, happiness and sadness, PTSD, and other things related to their experiences in life.
• Spiritual is a bit more nebulous but could be summarized as an ephemeral connection to something greater than self. This encompasses all faiths and also other philosophical viewpoints like humanism, stoicism, fatalism, et al. Which is why an atheist could also be spiritual if they are also, say, humanist

So these all interconnect and affect each other. Mental health issues have physical consequences. Physical pain can make emotional health plummet. Feeling depressed can cause someone to doubt their place in the greater whole. And so on

Personally I think you are correct that the picture can describe a mental, or probably more likely an emotional journey. But I think it can also describe a spiritual journey separate from an emotional one. Or both together, since they often affect each other.

Anyway, that’s just my personal take. I’m no scholar or expert. I’m just a man with a sixth grade education who loves animals