Hey there, thank you very much for the detailed reply! I really appreciate it. I haven't had the chance to fully dig into your code just yet, because of some assignment from other classes. But on the first glance I think I already vaguely understand why the first iterations of my grapple mechanic didn't work out -- which has to do with how the hook is created in the first place and how the layers and collisions work together. In the next few days I will look into that a bit more deeply.
Have a nice sunday and thanks again for your help!