Although Humans are the most prevalent creature types in Throne of Eldraine, that doesn't mean you won't get any value from Grumgully.
If you draft any other creature type except Human, you'll find that Grumgully is one of the strongest Limited cards in the set.
Of course, you must build your deck around it. Otherwise, it won't work as intended. In this case, Grumgully can be a bit of an inconvenience during your drafts, but other than that, it's a super strong card.