As I recall, the Earth and even what the Eve Gate is forgotten - possibly subject to some religious nonsense by the Sisters, but basically the “gate” if that is what it is is a shattered giant something. With EVE written on it.
There’s a difference between what we know as players and what characters know. And a lot of the early history is still unknown and subject to exploration. So yes, forgotten not even myth.
There’s quite a lot of known unknown in the back stories. Even where stuff is “known” it may be specialist knowledge - for example could you be expected to know the details of the latest archeological discoveries of sites in, say, Central Asia? Personally I couldn’t give even an overview of the subject. But someone who has spent a lifetime studying it will know it.
Knowledge isn’t universal.
So make a reference to the “old world” and people won’t know what or where you are talking about. It’d be like talking about “the old 'ole” and meaning a cave in the Rift Valley. Except we’ve more evidence of that cave than a citizen of New Eden has of Earth.
The only concept is that we probably have a common ancestor since we are all human, but where that common ancestor was from, no one knows
There’s a lot in being a simple person from the backwaters…