If you continue down this train of thought you eventually realize that outside of earth, velocity is just a number and all that really matters is the relative velocities of the two. So it's impossible to definitively state which one is moving or if they're both moving and if so how fast each one is moving. And then these sorts of things seem far less impressive.

And then it gets weirder when you consider that galaxies don't actually collide at all because they're so sparse and all that really happens is they pass through each other and maybe they permanently merge or maybe some of the matter in one galaxy joins the other one and they just keep drifting apart in slightly different directions.