Its a good metaphor, but I understand that not everyone may take to feeling like an alien.
But its only relative to other types of people and species.
If I managed to travel in space to another (exo) planet inhabited by intelligent beings, I would regard myself as normal, and the natives as being alien. On the other hand, the natives would regard me as being alien.
So there is two ways of seeing this:--
a) I could feel like an alien on planet Earth
or b) I consider myself normal as from my point of view, on a planet full of aliens.
And, for those who rather not use the alien metaphor there may be other metaphors yet to be discovered.