She was an incredible talent. With a unique voice. She died from melanoma - highly malignant skin cancer.
There are many tributes. Here is a recent one: https://www.theguardian.com/music/2021/nov/02/eva-cassidy-singer-songbird-25-years
I would add Songbird to the list of albums worth hearing. Most of the albums were released posthumously, but some of them are not very good as her unreleased and archived material is mined. Live at Blues Alley is my favorite. It was recorded just before her death.