Well said.

In no world can spaceships travel faster than light.

In a few worlds, there are simulations in which spaceships travel faster than light. Minor nitpick.

It is meaningless to talk of being the "first" or the "only" person to know a thing, when everything knowable is known within worlds that are in neither your past nor your future, and are neither before or after you.

It's still meaningful to talk of being the first or only person in your world; and, while this may not affect the point generally, the motive to independently work out something takes a big hit from the knowledge that you could just look it up.