Hey Divine Gaming,

The item you found in the red circled room can be used to continue upwards in the room with the red arrow to explore the rest of the demo. 

The very tall shaft in that room (with the red arrow) is designed that way to force you to explore the rest of the area since it leads to the end of the demo, it used to have platforms but I noticed a lot of people immediately went up when they saw it and ended up skipping most of the area unintentionally. 

I hope you're enjoying the demo!