There's a persistent myth that readers need to like the protagonist of a story. They don't. Literature is full of protagonists who are selfish, deluded, cruel, or simply exhausting, and readers follow them willingly for hundreds of pages.
What readers cannot tolerate is not knowing what the protagonist wants.
Not in the grand thematic sense — not the wound beneath the want, the need they can't yet name. Those can stay murky for a long time. But in any given scene, the reader needs to know what this person is after. What they're trying to get, avoid, protect, or destroy. Without that, there's nothing to track. The reader has no way of knowing whether the scene is going well or badly for the protagonist, which means they have no way of caring.
This is why want is such a useful diagnostic tool when a scene feels flat. Not "what is the protagonist feeling?" — feelings are internal and static. But "what does the protagonist want, right now, in this scene, and what's in the way?"
It doesn't always have to be dramatic want. It can be small and situational — breakfast, a good nights sleep. But it has to be present, and it has to be legible to the reader.
A protagonist becomes real to a reader through accumulated choices made in pursuit of something. Take away the pursuit, or make the choices arbitrary, and you're left with a name and a description. Which is a long way from someone worth following.