Itch.io has a free game assets page to help you get through your jam, and even if you want to make your own, it wouldn't be a bad idea to use those assets as placeholders until you've got your homemade assets finished. Who knows, you might run out of time to finish the art. If those don't float your boat, there are more at these links, but remember to ALWAYS triple check the licensing before you use someone else's work in your project:
I'd also suggest looking through these for 8bit music, but make sure you look up the tracks elsewhere to verify licensing, as this is an automated compilation of files once hosted on a now defunct website. http://brkbrkbrk.com/8bcdump/
Best of luck, I'm looking forward to what kinds of games we're going to make!