@Hounder : if I recall, the author comments that they were deliberately going for a weak MC. But ya Isekai is just a different name for Portal fantasy, there are common tropes, but being over powered is not a required one. In this case it is just what allows the MC to still be sane and alive after that abuse and neglect.
the foster father is not for quite a while, but there are non-jerks who do look out for her before she moves on to the next town and I think that is one of them.
@sjmcc13 Oh thanks, I was just hoping this doesn't turn into a trashy shounen/shoujo where every random attractive person automatically becomes a love interest.