[Varyon]

"Monsters" of various flavors were typically considered to be either a direct work of Satan or descendents of Lilith. Dwarves, gnomes, and halflings would probably be considered deformed humans at best, implying they (or their parents) have some degree of wickedness to them and are best avoided. Depending on how extreme the ear shapes are, elves may be able to pass as humans fairly readily - plenty of depictions of elves have them with ears that aren't that much different from human. Indeed, the difference isn't much more extreme there than what you see in humans when it comes to attached vs free earlobes. If you're talking typical anime-style elf ears, on the other hand, they may similarly be seen as deformed humans, although with the rest of them being rather attractive they may be seen as demons wearing a fair disguise.

Cat-Folk and anything less human than that are likely going to be seen as Evil, however.

As for nephilim, I think those were typically seen as the progenitors of giants - Goliath and his family - who were pretty much all wiped out during or shortly after the time of David. Indeed, most of the older versions of the Bible - including the Latin, as I understand - actually translated "nephilim" and "giants." So I wouldn't expect medieval clergy to associate any of the races (with the possible exception of ogres and other large folk) with them. Medieval Jewish scholars might be able to make a logical leap like that, but I don't think the nephilim were ever really seen in a positive light (see Goliath), so that's not really going to help them out.

EDIT: Muslims might see the various races as types of (or humans interbred with) djinn, which while not necessarily trustworthy aren't outright evil (IIRC, they have comparable free will to humans). "Pagan" people of the medieval time period are probably going to consider them as or as descended from nature spirits of various flavors, depending on the exact nature of that strain of paganism.