The truth about 'Attack of the Giants' is that the giants are actually all experiments.
A number of years ago mankind discovered the Giant Ape People clan, and mankind wanted to use them for military purposes, so the noble leaders extracted the DNA of the Giant Ape People clan for scientific testing.
And after years of research also finally researched the virus serum that can gasify into giants. But this technology is immature, not only the success rate is very low, and the side effects are very great, so this produced a large number of failures, and these experimental failures are giants.
When the serum mutated to produce a contagious virus, a large number of giants were born. The giants were made from humans, and they were not capable of thinking and only hunted humans. The giants that were able to control the virus were successful.
"Attack of the Giants" Final Season Finale Explained
"Attack of the Giants" ended with the last of the Unsullied giants becoming humans, and the end result was that the power of the giants didn't go away, and that Allen had fulfilled his destiny, and Mikasa was still in love with him, and that it seemed like everyone was returning to a peaceful life.
But the writers have uncharacteristically added extras to the work that had already ended, Mikasa even took her children and husband to visit Alan's grave, and such a move will undoubtedly kill all the readers, and from the back of Mikasa's husband that was released, he was in a wheelchair and was already very old, so many people speculated that Mikasa's husband should be John.
Mikasa still looks young, she wore a single ponytail and brought her family to visit Alan, which seems to confirm that she is finally free after leaving Alan, and all this seems to confirm the words of Alan before he died, he said before he died that he hoped that Mikasa can be in his heart this life, and ten years later, his heart will still remember him.
And all this seems to be fulfilled when Mikasa brought her family to visit Alan, originally thought that the power of the giants has really disappeared, but the fact is just the opposite, the island of Pa has been destroyed because of the war, so that all the efforts of the people have gone up in flames, and everything seems to be back to the original point.