I’ll explain this more clearly.
After you buy jump, you get something called “Jump lvl 1”. This is already attached to your default jump, so it’s already activated. However, you only jump slightly higher. If you really want to jump high, increase the level of your jump. Other ways to increase how high you jump is by increasing your speed stat, which you can do buy upgrading any of the physical stats (Constitution, Dexterity, and strength) However, dexterity is most effective to your speed stat. Lastly, if you can transform into ssj/higher arcosian forms to increase your speed, thus increasing the height of your jump. As for dash, it’s literally the exact same thing.
Overcharge enables you to increase the % at your ki bar, which increases your overall battle level, which effects all of your stats. You get extra speed, extra ki dmg, and extra punch dmg according to your willpower only (Strength punch dmg is always in place regardless of %)
Endurance is basically DBC armor, much like how diamond armor helps protect your mc hearts. So somebody with endurance will take less dmg than the person without endurance.