Art school graduate here, and my only advice is to broaden your sights and keep trying (if you want to). I've interviewed with FAANG too many times to count and every time it's crashed and burned on the comp-sci quizzes. Fuck em, keep looking. You'll eventually find a team that doesn't demand solving riddles that aren't applicable to your day-to-day CRUD. Take these jobs and you'll quite possibly learn the skillsets, or meet enough people, to get into the Big Co's without the riddles. It worked for me.

I feel like I have PTSD from Google and Amazon interviews early in my career.