Why are the starks the main characters?

Ned stark claimed to have fought and won against Arthur Dayne.

He supported a rebellion by his friend based on lies that was against the interest of his sister.

Then he is seen as some honourable person.

The starks are also mostly stupid. The only thing going on for them is infinite plot armour.

Edit: I would like to change "main characters" to "protagonists". Because everyone on screen is important to the plot amirite?