Hello Connor,
Sorry for the delay in getting back to you - I only log in occasionally given my schedule. You are right, the engine should rotate fairly easy since you are only fighting the resistance of the valve springs. You should feel resistance but not any compression resistance since the spark plugs are out. Can you tell me what position you currently have the crank shaft? Is it at 45 degrees BTDC? I assume you are turning the crank at the 27mm crank bolt and are rotating clockwise (from the perspective of standing in front of the car)? Also, did the crank or the cam gears move at all during you removal and install of the timing belt? Sorry for the obvious questions, just have to eliminate the obvious potential issues.

Dwayne