Heya!
The E-button actually inspects the points of interest, for example when you press E at the Overlook spot (where you used the bundle of vines) Edward says that maybe he could get some vines to lower him down there. All the points of interest have additional information when you press the E-button so, I very much recommend using the E-button if you feel like you're getting stuck :)
Thanks for the feedback and it was nice to watch someone play the game! :)