Thanks for the hint ;)
I replayed and read the dialogue a bit more closely, which helped clarify where to go. Still ended up bailing after too many failed attempts at grappling my way out of the warm up zone above the start. It's hard for me to maneuver the playerbody with wasd while holding down x at the same time (left mouse option?), and the punishment for failure seemed pretty steep (waiting to fall for a while, go grab the hook and get back to where I was when I died). I also felt like the range to land a grapple shot was too short for how I wanted to swing, by firing in front of me, so that when it connected I was at the top of a swing. Maybe it's just not built for that kind of movement.
I think I would have benefited from a slightly more constrained onboarding section, with geo built to show off the ideal use of the tool, and maybe with a ground beneath so messing up didn't hurt so much ^-^'