I've been searching to see if there are any hidden secrets. I found what I hoped would be a shortcut, falling off the level on the first bone then landing on the birds on the way back to get here early. The blocks weren't solid and I couldn't use the cpu which made me think it was unintentional. I then used the birds to climb all the way to the top right roof of the cross bones but there was still nothing.
It was still really fun to look around. I had a creature fall off the stage with me and then used it as an island on the way down too which was also pretty satisfying. Here's a shot I took from that.
Anyways yeah this game is quite a masterpiece!