You've made very good points, but I want to add someone else to your end list (to fill out the trio): Damian. All the adults you mention are on their way to being all the family Harry has. Sirus would also have been in that list.

What I find interesting is that Harry's family, if you want to call it this, has come to him after he was pegged by the Powers That Be (Voldemort, Dumbledore) to be Important. He wasn't valued for himself until before the beginning of second year, when he stayed with the Weasleys. Poor kid.