So I searched around and found only an old thread about this from March '23.
It seems in earlier versions it was possible to bind an active skills to LMB and still have it be the move/interact button, when not targeting an enemy.
This function was supposed to be fixed and it not working was a bug, according to the mods/devs.
It seems it is bugged again at release now.
Cause this a major oversight, coming from any other ARPG where one can have multiple things bound to LMB, especially move/interact AND a skill when targerting an enemy, or when using force standstill (often with shift) and then LMB would only use the skill.
That functionality is very practical and it’s just very strange (and hard for me personally) to not be able to bind the things like that.