You don't have to apologize for the long comment*, as I really appreciate all advice (especially if it's detailed) given to me! I tried replicating the screen bug, but I seem incapable of doing it as I don't have a mouse and it doesn't seem to work with a touchpad. I will still change the window settings in the update after the rating period. And about the mixels, I thought having different pixel sizes wouldn't be too bad, but I get why that's somewhat of an issue. I actually did compare sprite sizes during development, but only after I had already made the tiles and the player sprite, so I chose to roll with the pixel difference rather than redesign as to not risk running out of time.
P.S. Regarding level 6, try combining some of the things you can do with the spear.
*As you can see, I'm a bit of a long commenter myself!