Upon reaching the bottom part marked with a question mark, simply return to the other areas and a path will have been opened.
Let me give you one more compliment, you are a very talented person, it will be great if you do not give up your game and continue to improve this game, I really like it and I want to play the sequel to your game. I really like the RPG theme. You can make the cutscenes longer because they're pretty short now. Thank you for your game, I will be keeping an eye on the sequel and your other games. You can do it!