Well they are optional, and you can certainly leave them blank if they're really stressing you out, but I would advise you to find a unique facet of your experiences/hobbies/etc. and answer the questions. It's another opportunity to make yourself stand out in front of the adcoms. People always complain about long secondaries (and I'm not exactly arguing with them - some of these secondaries are really hard to fill out), but they're actually an opportunity for you to level the playing field. The secondary is about humanizing yourself. Give the adcoms a glimpse into who you are a little more personally.
I wouldn't rehash what you've already written, but try going really small. Focus on one specific story you haven't told before and draw the humanity out of it. You might feel like you've left no corner of your life unturned on the AMCAS, but I'd be willing to bet there's another story you can milk out of something you've done. For example, if you already listed your art hobby in great detail, AND spoke about what it means in your life, maybe talk about a time when you showed your friends something you made and they didn't appreciate it - how did that make you feel? Or how a small offhand comment by an art instructor caused you to reexamine the way you draw nostrils. Or how an artist friend spent all their money on tuition and ended up living on the street trying to sell their art just so they could buy a sandwich ... and that's what finally convinced you to go to medical school.
Just kidding. Don't do that last one. Even if it's true 😉.