Put some ink dots on a balloon and blow it up. The surface is expanding fairly well uniformly, and the dots are getting further apart. Now if you did the same

Put some ink dots on a balloon and blow it up. The surface is expanding fairly well uniformly, and the dots are getting further apart. Now if you did the same with a uniform spherical balloon that's inflating somehow, there's no center and no shape to the 2d surface. Similarly you could be inside a giant cake as it's cooking. Any two raisins will be moving apart and this happens the same way near the middle or halfway to the edge (excluding temperature/pressure unevenness). Now if you make the cake bigger until you can no longer reach the edges it all works the same everyhwere in the cake. If you take out the non-raisin parts, and the bit where you consider that there might be edges, and that the cake started already big rather than tiny, you get the universe.