If we are to ride on a hyperloop train, can ordinary man withstand the G force?

Yes, an ordinary man (or woman) would easily withstand the G-force when accelerating or decelerating. Keep in mind that a hyperloop pod wouldn't go appreciably faster than a commercial airplane; maybe 100 mph faster. Also, there has already been supersonic commercial airplanes in the past such as the Concorde and the Tupolev Tu-144 so the speed that a hyperloop pod would travel wouldn't be a first for commercial travel.

G-force is only felt during acceleration and deceleration. While a hyperloop pod is moving straight at a constant speed the sensation for the passengers of a hyperloop pod would be similar to cruising in a plane.