The process is amazing. It's a giant highly optimized molecular recognition library. Random diversity in antibody binding motifs is generated by guided mutation of the DNA coding for the proteins in the antibody. This wide repertoire is then screened for antibodies that react to 'self' molecular patterns in the body, and the B cells producing those self-reacting antibodies are deleted. One B cell produces only one kind of antibody.
There is also evidence that this antibody repertoire is further primed and refined by constant interaction with the incredible molecular diversity produced from the bacteria that live on our mucosa (that is, barrier interfaces with the environment like the lining of the gut and lungs and the skin).
The immune system naturally tweaks antibodies to make them more efficient at binding (Affinity maturation it's called). If you are trying to make a vaccine, you are better off starting off with an antibody which has already had all the hard work done on it.
It should be pointed out that the donor they used is actually infected with HIV, the antibody didn't protect him because prior to infection it wasn't affinity matured or present in high enough concentration.
If there was a heirarchy of medical treatments, vaccines would surely be at the top. A jab when you are too young to remember and suddenly debilitating fatal diseases that have plagued humans for thousands of years are no longer a problem. The immune system is unique in that you can give information to it, you can communicate with it. It's an information technology, actually. I think this is why vaccines are so fantastic, it is a treatment that collaborates with the body. Pretty much all other medical therapies involved taking a broken system and breaking it even more to achieve some kind of withered stability which is inevitability temporary and has consequences for the organism as a whole (eg giving steroids for rheumatoid arthritis, chemotherapy for cancer).
The seasonal flu vaccine is a global immune system in action. It's a molecular rss feed, an app update, a glycoprotein tweet whatever analogy you care to use, perhaps one day an individual's immune system will be part of a greater whole linked via information tech. The immune cloud it might be called.
And millions will still die because of war and poor sanitation and exploitation.