Tutorials are hard, I think the good news is that you already so much content that the need for a tutorial is there. That means a lot is going on which is good, I would rather a complicated, deep game than one that is too simple or boring. I'm sure you will figure something out.
Free movement could possibly solve a bunch of the issues you currently have all at once. Could allow people to experience things at their own pace (less need for a tutorial) plus choose how many people they fight between towns, allowing them to get more gear and level differently based on how they feel about it. Could also be a fun animation for the slime movement, just bouncing up and down as you move. Might be a really fun addition.