The first rare young humans could potentially run across in Elwynn Forest is Gug Fatcandle, level 4. Gug spawns in front of the closed mine entrance north west of Northshire, and he drops a 4-slot bag called the Fatcandle Bag.
Mother Fang (level 9) is also a very neat looking spider for new hunters to aim for if you like eye-catching skins. There is more info, screenies, etc. about her in this post: Mother Fang.
Fedfennel and Gruff Swiftbite (both level 9) can be difficult to pull by themselves depending on where they spawn in. It is possible to pull and kill their adds and then run out of range to reset these rares though.
Speaking of adds, Thuros Lightfingers (level 9) spawns in a small camp with three adds very close to him (two adds pictured in the screenshot below). If you try to pull him all four will follow you. I was able to take on all of them with my ironman toon (you can see the hairy fight at the end of the video below) but it sure had me a bit nervous so be careful!
All of their spawn timers seem to be fairly close to the 30-45 minute range.
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