Jeremy Thomas was a British film producer who worked with some seriously talented directors over decades. He produced The Last Emperor, which won a bunch of Oscars back in the late 80s, and Sexy Beast, which was this wild, intense crime film with Ben Kingsley that came out in the early 2000s. He wasn't just doing commercial stuff either - he worked on films by David Cronenberg, Bernardo Bertolucci, and other directors known for taking real artistic risks.
The reason people in film circles care about his death is that he had this track record of backing challenging, unconventional movies when studios weren't always willing to take those chances. He produced stuff that's actually held up and is still talked about, which matters in an industry where most films get forgotten pretty quick. If you're someone who appreciates cinema beyond just blockbusters, his projects are the kind that remind you why good filmmaking still matters.