You most certainly can jump without gliding with Abi. Just don't try to jump when you are off the ground. ;)
As for difficulty, yes level two is difficult, but it has been completed by many players, so you probably just need to practice your movements. Here's a tip about Abi.
She uses velocity to give you a boost, so if you are falling, and you use Abi, you will jump way higher than if you just try to double-jump.
Most of level two's difficulty comes from timing sliding under the branches while being chased by the Wood Troll.