I had posted the game, but unfortunately, due to it being the first time ever doing this, I didn't know I had to zip the file and upload that, and instead just put the .exe. Is there an way to change the file in the post or is it impossible?

Yeah, if you go to your game's main itch page and click Edit Game at the top of the page, there should be an "Upload Files" button where you can add the zip.

Yes, you can still upload new files, and the jam organizers encourage you to upload fixes even during the rating period. I'll rate your game once you have a working build up.