In this image, we can clearly see that the shooter is still on his feet, and there is no image which shows or suggests that he was ever pushed down to the ground in the garage.
But, Ruby said that when it happened to him that he was pushed down to the ground. Let's also consider all the talking that Jack Ruby reportedly did, "Hey, I'm Jack Ruby. You know me." Etc. Well, it's very obvious that Garage Shooter NEVER spoke and NEVER tried to speak.