At the same time I agree with Casual42. The jump physics aren't good enough. It is better to add a constant force (weight) or acceleration. Now there is an "invisible wall"at the top of the trajectory.
Yeah, I really should’ve worked on the movement more. I’ve figured out how to add a “deteriorating” jump that gets weaker over time, so I’ll be sure to add that next time I make platformer. Thanks for the feedback!