I also never knew this about Kitty Genovese, but I do know that, in fact, many of the dozen (not thirty-eight) people who witnessed some part of the attack (which took place after 3AM, on a chilly night in March when most people’s windows were closed) tried to help in some way.
One shouted out his window for the attacker to leave her alone, which did successfully scare the man off temporarily.
Another called the police but, seeing her still on her feet, said only that there had been a fight but the woman seemed to be okay.
And when Kitty Genovese was finally attacked in a vestibule where she couldn’t be seen from outside, Karl Ross, a neighbor, saw what was happening but was too frightened himself to go to her rescue–so he started calling other neighbors to ask what he should do. Eventually one of them told him to call the police, which he did, and the woman he called, Sophie Farrar, rushed out to help Kitty even though she didn’t know whether the attacker was gone.
Kitty Genovese died in the arms of a neighbor who tired to help and comfort her while they waited for the police and ambulance to arrive. Kitty was in fact still alive, although mortally wounded, when the ambulance reached the scene.
The man who saw the final stabbing? Who panicked and called other neighbors first instead of the police? The man who said, infamously, that he “didn’t want to get involved” because he was reluctant to turn to the police for help? He was thought to be gay himself. He was a friend of Kitty and Mary Ann’s. After being interviewed by the police he took a bottle of vodka to Mary Ann and sat with her, trying to comfort her.
So, no. I don’t think the evidence indicates that Kitty Genovese’s neighbors let her die because she was a lesbian, because Kitty Genovese’s neighbors tried to help.
(Also, going by the content of the murderer’s confession, it was indeed a random attack.)