Tarkin definitely is the main villain of the first film. Not the highest ranking, but I don’t see how anyone says that the Emperor was a real presence as a character, and wasn’t even revealed as Force sensitive as you say.
Also recall how dismissive the Imperial officers were that one of their co-workers adhered to some mystical cult? The '77 Star Wars universe was far more secular than later installments, with the magic mostly relegated to generations past.