I am sure most don't mean that way, they should be happy to be friend with you (therefore not treating you sub human)
But being in relationship is another matter, many people have many preference, for example I don't date women with kids, or certain skin colour, it isn't very nice for people within that bracket but that is my preference. I am sure someone would include those people within their bracket though.
Not wanting to date someone does NOT equal to treating them sub human