I just started playing this game years after I did so last time. All appeared well until I tried to save the game right after the first cutscene. The gammsaav did not react even though I had it equipped, then when I tried talking to the NPCs, left clicking when standing near then did absolutely nothing. Is there any way to resolve this?

You need to change your key bindings. Left click defaults to Jump and maybe Menu Confirm, but not the default interaction (default is E key, I think). Use the launcher utility to redefine your key maps.