If the big bang originated from one point in space - shouldn't all of the galaxies in the universe be moving away from that one point - and not expanding from each other in all directions?

Answer 1

try this experiment.
put some food coloring into some water, fill a balloon with this solution say 1-2 quarts worth.
tie off the balloon with a string.
hang this balloon outside from the string so it is free in the air.
take a dart or similar object and throw it at the balloon.
look at the pattern of food coloring on the ground as it will give you your answer
obviously in space there isn't any gravity to speak of. as all the food colored water
will fall to the ground due to gravity

Answer 2

The Big Bang theory suggests that the universe is expanding uniformly in all directions rather than originating from a single point in space. Galaxies are moving away from each other due to the expansion of the universe, and this expansion is happening everywhere, not just from a central point. The idea of a "central point" from which everything is moving away is a common misconception.