I simply edited the image shown in-game that lists the game's controls. I tried to match the style and font of the original, highlighting every key that does something in-game and listing them on top.

Right-click can be used as a back button in certain menus.

Space speeds up and skips certain fade-ins/fade-outs and X and C skip through text really fast.

For skipping text during a speedrun, you generally want to be holding down X or C + Space (I usually use X). Sometimes certain parts of cutscenes/dialogue unhold the keys you're holding, so you have to press and hold them again immediately.

TAB also usually selects the 2nd dialogue option in a text box (for example, during the Sal cutscene where he gives you warp orbs, holding TAB buffers the input of selecting the 2nd dialogue box, which is the correct option to end his dialogue).

Lastly, I shouldn't need to say this but the menu can also be controlled with WASD and Arrow Keys.