That is a ton of changes. I would love to see stat changes be more beneficial, but I am not sure that doing it ALL AT ONCE would bode well. Try doing pieces at a time so that you don't have to redo a whole bunch of stuff.
I am all for the no capacity stats, but add like a code with an exponential equation that increases the level up cost per each stat level. Like "LevelUpCost(x){ x^1.5}" where x is whatever the current stat is.
Something is charming about flying to monster level 50 and juice farming. Making stats purely use-based is a lot less fun, and also lessens the need for juice farming. If you want the infinite terrain to be a thing, you should also have the infinite stat to be a thing.
As you go farther, monsters gain size. What if you added size as a stat so we could actually reach monster hit boxes more effectively? Or size could increase residually as you gain more levels.
If you want to add a gets-better-as-used thing though, maybe apply it to weapons. Like weapons gain levels with each hit they get or something and have a max level depending on what rarity you found them with.
I think there is little use for jump height but spirit would be an absolute plus. Like extra spell damage or pineapple, rubber ball cannon, or frizzX damage.
What you have done so far is really cool, fishlicka. Everything can always be improved, but I personally would not like to see the game changed so drastically.