There's an even EASIER way to win 1-3, only losing 1 life. First collect the acorns above and collect the green key. Then, collect the acorns below without collecting the red key. Then collect the red key with a jump that will kill you between the red key and starting platform. Then jump on the corpse of your previous animal and stay on the left. It will slowly push you to the golden acorn. + This comment so others can see!
I like the concept, a really fun game. But most of the characters look suspiciouly the same. The controls got a bit annoying eventually too. Nice game. 4/5.