I think this was an interesting take on a platformer.
I have seen others in this jam use a similiar mechanic but regardless, I think you have managed it the best so far. I used the A and D keys rather than the arrow keys due to the recommendation on the page and noticed the comments mentioning the bugs but those can be fixed after the jam if you wish to take this further.
I liked the variation in the levels it added some complexity, if you continued this you could make levels that mix ideas from these levels together such as the anti grav and the spike balls being there at the same time and you must navigate through while switch gravity that would be both interesting and very difficult.