What you're *mostly* seeing is humanoid shaped creatures with reptilian/draconic traits. Some have stronger reptilian traits (dahaka, ladonid, reptus) while others are only slightly tainted (mordredin). You have a reasonable guess that you can get mordredins from elves, humans, etc. and whatever source of reptilian essence makes them. Ladonids, dahaka, kerren, etc. might be a further corruption of man-like creatures, or their own race entirely. They might be a pre-existing unknown reptilian race, with draconic properties given to them....
What you do know is that they speak a language that shares an ancestor with many of the currently spoken ones on the great ring.