In Octavia Butlers "Speech Sounds," how does the author's characterizations of the story's protagonist and antagonist "fit" the story's central conflict?

In Octavia Butler’s “Speech Sounds” there are two protagonists in the story. Rye is a young woman trying to survive after a pandemic illness results in massive deaths and leaves the survivors without their ability to communicate. Some have lost their speech, others the ability to read or write. The world has become a violent place filled with desperation and loneliness. Rye is alone and on the brink of suicide. She meets a man she calls Obsidian. At first she fears him but after a brief interaction she begins to trust him and actually becomes attached to him. Although impaired from the illness, they are able to find a way to communicate with each other without conflict. However they soon come across the antagonist in the story, a man who is threatening a woman and who ends up stabbing her to death. Obsidian kills the man, but his last act before death is to shoot Obsidian. Rye is again alone.
The central conflict of the story is the disease and the lack of communication within society. The real antagonist is the disease that all of the characters are fighting. The aggressive man represents the disease and its cruelty as he takes everything again from Rye, leaving her alone again. Rye, the protagonist, ends the story with purpose and hope when she realizes the two surviving children of the couple can speak and communicate.