I encountered a problem very early on in the beginning where I'm trying to pull a lever in the city you enter after the prologue section as an angel. However what I think is the action key (Use Interactive) doesn't seem to work for me and I've tried it on both 3dfx and D3D version of the game

You want bind Talk/Activate key, as Interactive is just selected type of power, not action key. Also selection of powers not always work because of their different categories so even if you use menu selection for all of them you still need left click on them like on weapons, there are different keys for cycle through different types

Thanks for the reply! I was confused since the game kept mentioning "action" key yet they didn't specify in the input binding what the "action" key was. I appreciate your help! :D