As far as I know, there are generas of fiction where it is very unusual for any characters or animals to be killed, such as many types of children's stories.
And there are probabily many generas where it is common for most of the characters to die, often by violence, such as Elizabethan tragedies.
And there are other generas where the number or precentage of characters who die may vary from zero persons and zero percent of characters to one hundred percent of characters. For example, there are many science ficiton stories where nobody gets killed, and other science ficiton stories where a natural disaster exterminates the entire human species. Except for some sub generas of science fiction, such as military science fiction, science fiction readers tend to start a story without any preconceptions about what percentage, if any, of the characters will die during the story.
So if your novel is, for example, a serious drama, readers would not have a preconceived idea of how many of the characters will die. Some serious dramas have no character fatalities, others have many. If your novel is a lurid melodrama, readers may expect that a lot of characters will die, many violently.
And the more serious and "respectable" you want your novel to be, the stronger the story reason and justification for each act of violence or accidential death should be. And the more subtile foreshadowing there should be.
As a general rule, the more characters who die in a story, the less the emotional impact of one death will be, and the less unusual each death will seem. Thus in a story which is a bloodbath, the readers will not question why a particular character is killed off so much as question why the few surviving characters survived and did it make sense for them to survive.
So if only the villian and the gay character die in the story, the readers may think about both of the deaths, and how much they may have been the just fates of the characters and how much not, and the more critical readers may wonder why the author decided to kill those characters off and how much senses those deaths made in the logic of the story. So in such a situation you may be considered homophobic.