Do you believe there are aliens walking among us?
Very unlikely.
It would be more likely tha tpersons from an alternate nultiverse earth managed to hop universes. However, I think it woudl be liek the TV show "Quantum Leap" in that they woudl have no way to return to their universe fo origin reliably, and woudl nto be able to cmmunicate with their universe of origin either. Still it is a better possibility thatn aliens from other planets livign among us... yet both are highly unlikely.