It's an odd coincidence to come upon this posting today. For some reason, I was remembering SuAnne Big Crow today. She was a Lakota teen from the Pine Ridge Reservation in South Dakota, who was killed in an auto accident at the age of seventeen. She was an excellent basketball player. The Soviet Union awarded her an medal for her excellence in athletics.
Before I say more about her, I'm wondering if anything about the sudden death of your main character results in any understanding on the significance of that character's life.
SuAnn Big Crow did something absolutely stunning on the basketball court one day before the game even got started. Her Reservation team was to play a non-Reservation, South Dakota high school. When her team came out, the other SD team tried to make jerks out of her team by mimicking "Indian things," like whooping while slapping their hands over their mouths repeatedly. Instead of shrinking in embarassment, SuAnn spread out her athletic jacket and did a Lakota dance right there in the middle of the floor, bringing the jeering crowd to a place of silence, respect, and awe.
She had great dreams of a teen center on the Reservation, a place to go without drugs or alcohol. She had a good chance of making the Olympics. Though her own life was cut short by a "senseless freak accident," much that is meaningful has come of her life. I am not a believer in "everything happens for a reason," so I'm not suggesting that sort of thing.
I think that agent who rejected your work on the basis she noted has a limited imagination if she thinks death by a sudden accident automatically negates what the novel had originally set out to do. That would be the case only if the author had not thought the book through, got tangled in the plot, and then conveniently killed the main character off to end the book somehow, any which way, just to get it done. You don't sound like a writer who did that. When that agent says she would not be able to sell you book, I'm sure she is telling the truth. But that probably has to do more with her prejudice against accidental deaths in a novel and her limited imagination, than the quality of your book. She didn't even give it a fair chance.
If you have any interest in what became of SuAnn Big Crow's dreams, the example she set by her life, and her hopes for her beloved Pine Ridge community and for teens well outside of it, here is a link:
http://suannebigcrow.org/1spiritofsu.htmlI'm not suggesting you write a story something like hers, but just pointing out by way of example that nothing of what her life started out to be was "negated" just because of that accident.