I did the first things except the code and it works better now, thanks! Tried the code and it was creating some physics problems. I found a solution to just be able to jump before 0 and works great.
My only problem is that I don't know how to make the ball to not jump while mid air. Since this isn't platformer but physics, it doesn't do that automatically so it has infinite jump, and I only want one. I found solution like the image and it works great, but found out that at the tiny window of 0 to 20 while mid air, if you press the jump button it will jump.
I tried many different things combined with touching ground too and this is the best solution so far with this small problem. Tried to isolate the Velocity X only but didn't work. I don't really know what to do anymore after I tried many things and my head is hurting a lot haha