A delightful game - the spritework is beautiful. Figured out I could negate knockback by swapping characters, which helped me a bit. Squirrel was definitely my most-used character, it seemed to even be able to jump slightly higher than the llama! It seems like WASD isn't quite coded properly as I couldn't seem to use W to initiate vine climbs, but arrow keys work fine. Climbing can be a bit finnicky, I'd prefer to just be able to hold up rather than have to let go and press it again in order to get the next vine as some of those jumps were super tight.
All in all I had a fantastic time exploring the mountain, I'd definitely say this one belongs on the NES. My final score was 10/10/9, couldn't find that last fish (I assume) for the life of me!