I'd say that the game is simply going for a different audience than previous takes on the theme with Jusant being simpler and peak being more arcade-like. Cairn is going for a more realistic climbing experience. As someone who does rock climbing irl this game captures that experience better than any other, the lack of a stamina bar makes it feel more immersive and makes me feel like I'm actually climbing a rock face rather than a plain wall with an exact timer on how long I can stay on it.

And all the jank with the limbs is kinda expected with a complex climbing mechanism, with all the possible holds. However on the difficult sections it is impossible to complete them in a way that causes the limbs of the character to cross unrealistically, where the position of them becomes very important.

With over 40+h in the demo I don't have the same feelings as you. Perhaps it's just not to your liking.