It's a really good start, not enough games do combination animations for enemies. Slime x spider for instance.
In terms of game critique, I'd recommend making some of the jumps easier, and removing that kill pit at the start of level 3 to the left.
In terms of bugs, if an animation starts with 3 or more entities, it will play the default running animation. Also, after beating all 3 levels, I couldn't seem to replay them anymore from the main menu.
I'd love to see more enemy gangbang combinations, though I know that takes a lot of work though considering the permutations. Having more than 2+ entities being able to animate would also be nice to see, but again, a lower priority than actually making the game.
I'll be keeping an eye on this, good work and good luck dev!