I was procrastinating all day but finally got settled down to make some progress. First of all I cleaned up the climbing logic and added comments to everything (for when I release it). I also fixed the climbing pose when idle. Next up was making attacks. I first needed to make a weapon, so even though this character is a template, I gave it the weapon I intend to use for my first game. I then set up attack animations and made it distinguish between standing, crouching and jumping scenarios (I haven't made the jump attack yet). I'm becoming used to disabling everything in my timelines. There are several ways to do this but currently I'm using signal manipulators as killswitches on all relevant inputs, and switching them off with a keyframe that runs along my other animations, as well as all procedural animations. Now my animations work well, and I set up hitboxes during the timeline that inflict damage on any enemy it strikes (setting a collision with the weapon itself is risky).
With all that in place, I could drop in the enemy I created earlier, and have an actual battle! It shoots arrows at me that I must duck or jump, and I can hit it back with standing or crouching attacks. This is all super basic in terms of gameplay, but it's so, so rewarding having built it all from scratch!
Edit: Also found a neat tip: when modelling negative objects, it can be annoying when you move a previously made object into the same space and it gets intersected as well. If you clone the object, it isn't affected by the negative object since it's further along in the "list".