Nami just proves that being physically weak doesn’t necessarily mean you’re useless. She has intellect, navigation skills which are god tier. Without her I doubt Luffy could even reach the Grandline let alone survive for as long as he has. Also Nami is extremely loyal, as she proved times and times again putting her life on the line for Luffy.
She’s just so humanlike, not a monster superhero with a ridiculously op abilities. Normal people like us can relate to her flaws. That makes her such a good character.
