clumsy ball python

Okay so I heard that ball pythons in general are clumsy but I still worry.. my little guy Pretzel sometimes falls off ledges in his terrarium (he climbs up his branch and then somehow climbs into the ledge of the lid of the cage but he cant grasp hold or something and he falls onto his substrate or water bowl..he seems fine otherwise but it still concerns me
Also tips for keeping up humidity in a 20 gallon terrarium? I feel like im always spraying my substrate (the reptile cedar cypress mulch) and i have some of the screen lid covered. I dont want it to get too wet in there and get moldy, is a humidifier a good investment?

How are you heating the tank? Lights and CHEs will dry out the air. I had to switch to eco earth and cover the lid to maintain humidity in mine. When he grows out of that tank you should invest in a proper PVC tank.

They are GROUND DWELLERS, yes they can climb however unlike semi-arboreal and arboreal species they are just clumsy, and that's just the way it is.

Humidifier is a good investment. It makes snake-keeping so much easier, when they are in kept in a dry room. (which is most heated homes)
I use a humidifier just for my own sake, in winter.