I'd like some clarification on the latter part.
Harry's mother's love prevents Voldemort from killing him as a baby when he should have died. I understand that part. I also understand that Voldemort turned Harry into a Horcrux inadvertently.
What I don't understand is anything after that:
- Does Harry's mother's love mean that Harry was protected against future attacks by Voldemort? The plot heavily implies that it wasn't a one-time deal, and that it was the reason why he wasn't killed outright when Voldemort cursed him in the Forbidden Forest. So was Harry immune to being killed by Voldemort all along? If not, why was this time special?
- Why does it matter that Voldemort resurrected himself using Harry's blood? If he hadn't done so, Harry's mother's love would still be in effect presumably. What changed by Voldemort doing so?
Well as Harry was growing up he was still protected by his mother's love, through Aunt Petunia who was of the same bloodline of Lily, as long as she agreed to house him. But when Harry became of age, and the Dursleys left, the protection broke, and Harry was vulnerable, or so we thought.
When Voldemort resurrected himself using Harry's blood he unknowingly doubled the blood bond of Lily, thereby making himself Harry's life reserve, so to speak. So when Voldemort used Avada Kedavra on Harry in the forest, he killed the part of his soul that resided within Harry, but while Voldemort was still alive, he was tethering Harry to life, so Harry couldn't die at the hand of Voldemort.