Which Harry Potter character do you think should not have been killed?
I am going to go out on a limb here and say it should be “Sirius Black”.
Let me prove to you why.
There is a child who was never loved by his family, He was burnt out of his Family tree. He was the man who was not even respected by his own family elf(Mind you that’s a big thing). He used to live with James Potter during his school breaks. Imagine the empathy you have for Harry when he was with the Dursleys. It was the same with Sirius
He knew that the dark lord wanted to kill his best friend, Yet he couldn’t do anything about it. He went to question Peter Pettigrew about and was thought of as killing him.
He was thrown into Azkaban for a crime he did not commit. He stayed there for 12 years and was one of the most heavily guarded prisoners over there.
He broke out of Azkaban only to kill the one person who was responsible for the death of his best friend, Such was his loyalty.
At the end of Prisoners of Azkaban, he reunites with Harry and dreams of staying with his godson, which is blown away when Pettigrew whisks away.
He had to stay away from Harry again, and then in OOTP, he died fighting beside Harry. This man in his entire life didn’t have Love, he couldn’t spend time with his Best Friend or his godson.
Let me remind you Harry Potter story grows around love, sacrifice and Loyalty.
Yet Sirius who had all of those traits didn’t find happiness. NOT FOR LONG.
He deserved to live, He deserved happiness. He deserved to see through all of it.