How would you describe an extremely ordinary character?

[Someone]

Ordinary to an almost cliche degree, the most average of the average...
That's the kind of character I want to write. Well, for now.
On the inside, she's going to be a delusional girl who thinks that she has been rebirthed from another dimension and was given another chance to save the world. She regards other people as her servants, and she thinks that she's above everyone else because she has a "legendary power". She even makes up her own battle moves and names.

But that's only on the inside.
I want an extremely ordinary character.
Can you please give a description of their personality?
Or just list some adjectives you think describes a boring person for all I care.

I'm basing this character off of Rikka Takanashi from the anime "Chuunibyou Demo Koi ga Shitai!"