Information does take time to travel. That is why blocks are not set at 1 second, or even lower, at this moment in space-time, but at 3 seconds. When everything goes fiber, that might even go to higher speeds, but for now, 3 seconds is fine.
It works even under high pressure, so I think I do not get your conclusion nor your follow up question.
How is all this information stored in a decentralized way? who holds this massive blockchain?
It is stored on many different computers that have the right hardware to deal with this. With internet connections that can handle it.