That assumption is entirely not true. In fact, character is actually more of what happens in the story.
Why?
Well, for you answer, you'll have to know that roughly, there's about three different plot types.
Romance.
The Man Who Learned Better (Ebeneezer Scrooge for example).
And, The Heroic Quest.
(This is the same as what you'd learn in OYAN, by the way).
Each modern day plot has elements of each of those basic plot types. And those are plots, what actually happens is plot as well, but here's what isn't plot.
The book circles around the Main Character, and he (or she) learns throughout the book. That isn't the plot. And often times, that's the most important thing about the book.
We respect changes in the character.
Hard changes.
Ones that leave the Main Character changed dramatically.
The plot is just to further along what's happening inside the Main Character.
The Character travels from point A to point B (and this isn't traveling physically, though it could be that as well).
The Character travels from point A to point B (and this isn't traveling physically, though it could be that as well).