Wow this was cool! Setting aside the lack of audio, I quite like the presentation! The monkey model is charmingly idiosyncratic and the colours and shadows were well judged. I'm of the opinion that a virtual camera shouldn't be constrained like a physical camera, so I think your implementation was just right: felt like I could always see what I wanted to see. I really like the way you use the grab action for all interactions, makes the world feel consistent and tactile. The hand-tiring mechanic was a cool way to make the player swing more like a monkey and introduced a nice little awareness challenge. I also think the way you could stretch and slingshot while grabbing on the ground is neat, reminds me of the rubber band in Sheep, Dog 'n' Wolf (US: Sheep Raider).
In terms of improvements, a nice bit of QoL would be to hold the hand out while holding grab and to initiate a grab as soon as you get in range. I assume you're using a spherecast for finding the grab point, might be better to use a thicker radius or to move the aiming to a separate mode and go purely off of distance to the monkey by default. Might also be nice to be able to apply a bit more force to your swings starting out (so that you're able to start swinging from a still start, for example), though that might de-emphasise the sense of momentum too much.
I also wonder whether it could be fun to let the player decide whether to spend their banana on upgrading both arms or one in particular? Could have a dedicated grappling hook arm and a swinging arm. Anyway I look forward to seeing how you develop this further!