system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Wars] Why could the dark side not be sensed in palpetine?

Also how the hell are they able to jump and fall so far?
gpt
Palpatine is possibly the galaxy's greatest master of deception. He spent decades insinuating himself into galactic politics, and put much work into masking his presence. He allowed it to grow very slowly, manifesting as the "fog" over the Force that the Jedi Council detected but could not penetrate. The defining aspect of the Jedi Council, as well as the greater Republic in this time period is deep-seated complacency that left them ill-prepared to deal with any of the problems Palpatine created. He used their system of bureaucracy directly against them.

As for the latter, Jedi are able to move things with the Force. It's not a stretch to believe that they can self-levitate. They are able to enhance their natural abilities directly, too, as you can see when Luke Force-jumps out of the carbonite device, when Qui-Gon and Obi-Wan use Force Speed to get away from the droidekas, and when Yoda does anything with a lightsaber.

Edit: If you ask me, there's no good reason Mace Windu should be assumed dead, thanks to the abilities already displayed elsewhere in the movies, much less the EU.