Very cool, I like how you have him swing his arms sideways and land crouched. That gives a nice contrast in terms of body shapes across the shot. Good thinking!
You mentioned that the keys are aligned, so for your next pass look out for offsets in your movements, so that different body parts start and stop at different times.
My only comments would be about the weight distribution at the beginning. He leans to the left (I'm looking through the persp camera), but the screen right leg gets off the ground a bit early. So on x7, I would have his left leg still on the ground so that the root is a bit more leaning over his right leg, then lift his left leg, but push the weight shift more. So on x9, it doesn't look like he's over his right leg enough (it looks better in the front view camera clip, but the persp is more interesting so I would base your anim on that view and push it so that it works towards that camera).
ON x18 you seem to overstretch his legs, with the IK controllers being still on the ground. I would bring up the legs, and I would also rotate down his left foot, so it doesn't get off the ground horizontally.
As you spline out the keys, it will help the arc of the head, but just in case, make sure that when he goes down and up around x14, that there isn't a direction change over one frame like now. You can drag the head a bit as the body goes up for that.
Watch out for his right arm once he jumps. It swings to the right, then left, then back to right and finally left until he lands. I think you can simplify this a bit more, so it's not so frenetic.
The head could also have a visible impact once he lands on x27 and on, just a little down/up move so it's not so stiff.
Great first pass! You mentioned that you needed to go back to basics, but you're kicking butt, I don't see you struggling at all!