He is/ was the first guardian or "risen" to be created. If there has always has been a speaker and the risen were created after the collapse it's safe to assume the speaker was the very first of his kind AND he holds the soul of the traveler. This "speaker" has always existed and has the ability to commune with the traveler yet we don't know how he got this power to talk to a dead god. The god (or traveler) is not dead but merely he changed forms and is now the speaker. The traveler was the first ghost so-to-speak and his choice was this form (referring to the speaker) and he imbued this form with his soul. This is why there has always been a speaker because the speaker was the first risen and the speaker IS the traveler. Any feedback would be great! Edit- 1) read the tags I put theory in there for a reason 2) I know this has no basis but is still a cool idea that I thought up. Most likely isn't true but still a cool idea.