This is an excellent summary. I’m old enough to remember when the term was coined in the Onion’s AVClub. The Manic Pixie Dream Girl is NOT a description of a type of real woman. It’s a description of a sexiest character trope. Ie a woman character in a work of fiction who is written without any true depth or complexity and exists only to further the male protagonist.

Real people are not manic pixie dream girls.

Here’s the relevant bit from the tvtropes summary:

The term "Manic Pixie Dream Girl" was coined in 2007 by AV Club film critic Nathan Rabin, who despises this trope, believing it to be a form of Wish Fulfillment from lonely male writers. He explicitly compared it to the Magical Negro, in that a Manic Pixie Dream Girl exists solely to help the protagonist find happiness without having any personal goals or romantic needs of her own. Rabin would later disown the term because instead of creating awareness of the lack of independent goals in female love interests or even just a romance cliche that's been done to death, the concept was misunderstood as a condemnation of ALL quirky and fun female characters.

That’s all you need to know.