I think it could work. Here’s a background idea for some aliens:
When the dimensional event occurred on Earth, a small fleet of exploratory craft were travelling nearby. As their faster-than-light drives utilised these dimensional physics, the event caused them to malfunction and their ships came crashing down to Earth.
The alien survivors are without a means to contact their homeworld, low on supplies, and facing a world filled with unimaginable horrors.
I imagine them working a bit like groups of raiders, but with very different abilities and equipment. This strange world is incredibly hostile to them, and it’s unlikely that they would see the player as any different.
Maybe alien crash survivor could be one of the weirder challenges. You start with some fancy items, but like Churl you cannot learn from books, and human NPCs are always hostile.