Yes, I think Bran is the world's memory, but it's unclear why that is as important as it sounds.
The following are some things to consider...
As a point of interest, the untitled Prequel 'Age of Heroes'/'Long Night' TV series (in development/Pilot filming this summer) synopsis states,
"Taking place thousands of years before the events of Game of Thrones,
the series chronicles the world’s descent from the golden Age of
Heroes into its darkest hour. From the horrifying secrets of
Westeros’s history to the true origin of the White Walkers, the
mysteries of the East to the Starks of legend, only one thing is for
sure: It’s not the story we think we know."
So we have to consider how important is it that Bran knows everything vs who he tells what things too, meaning, "what good is it, if Bran knows things, but doesn't actually tell certain people the whole truth?", because essentially all of Westoros is built on lies!
Another thing to consider is that after the "Hodor Paradox" combined with what the previous Three-Eyed Raven told Bran about "The Past is already written. The ink is dry" it seems that we are in a predetermined universe in a cycle cosmology [ghost] story. Well at least until we break into a new cycle, then who knows, maybe free will becomes more possible?
But if so, if they are in a predetermined universe, then even Bran's actions are "moot" because he's just fulfilling his destiny, as opposed to having any real power to change anything and therefor everything he says, is not necessarily the exact truth, as much as that is what he needs to say for other characters to fulfill their roles of destiny too! (ie: if they think Bran is important, then they will be compelled to do "a, b, and c".)
And one last thing to consider, is if Bran is the world's memory, what good is it, if he ends up either dying before TNK or being the only survivor? Now I'm doubtful that Bran being the only survivor will happen, but as a possible scenario it calls into question his statement, unless time travel is involved for Bran and he gets stuck in the past, but even then, unless he can make an alternate reality, it seems moot -- still just doing what he has already done.