Author as narrator of their own story

In first person, the narrator tries to convince the audience that they (the narrator) are the point of view character.

The most natural use of first person is when we tell stories about our own lives, because we literally are the point of view character (even if we lie about details in the story).

graphic showing narrator recording themselves inside the story. They are wearing a pink dress and looking at a shampoo ad.

This is a form of story that we might call an account, recount, memoir, or autobiography, depending on the context. (As opposed to narrative, which is purely fictional.)

Here's an example from Growing Up Disabled in Australia:

The treatments would work for a while. They painted my body with pastes and lotions, wrapped me in bandages, zapped me with UVB light every day. After a month or so, my disease would retreat to a socially acceptable norm, and all the medical staff would gather at the end of my bed, congratulating themselves on their cleverness. I was just a passive recipient of their wisdom, with no agency or knowledge of my own.

Grammatical first person means using the pronoun 'I' when referring to the point of view character.

But apart from that, everything looks again like third person limited subjective.

And subjectivity is the whole point of first person: this point of view lets the narrator filter everything directly through the point of view character's perceptions. 

The only confusing thing when applying our highlighters is, what isn't a perception in first person? All of the character's information about the world is coming from their senses, so in a way it's all perception and the lines between highlighters become blurry.

Here's another example, and again the choice of highlighter is completely debatable:

Today I took my greyhound to the vet for a chest x-ray, to check if she has any cancer in her lungs. Last Christmas she had a hind leg chopped off because she had bone cancer in the knee. She seems completely better now, and I'm confident her scans will come back clear (though I'd be sad if they didn't). On the way out of the surgery we ran into a golden lab who'd had his nose removed. At the end of his snout there was nothing but pink gristle and dark holes.

Try writing your own first person account from something in your real life, and see if you naturally describe actions, environment, thoughts & feelings, and perception.

Using first person, write a brief description of an experience from your own life. Try to use as many elements as you can.

What we saw here was a case of the narrator legitimately being the point of view character.

But what if they only pretend to be the point of view character?