Even with how popular the franchise was becoming in the United States, Pokmon was in its infancy and baseball cards were arguably the TCG to beat
While there is a multitude of strong cards that synergize with humans such as "Sigarda, Heron's Grace" (which provides all humans with hexproof), there are countless powerful humans that can provide utility for nearly any scenario
The Giant synergies will be a bit harder to find with 80 cards, but were adding a lot more digging to the deck, so it might just be worth it
Contagion usually trades two cards (the Contagion plus another black card) for two creatures, which seems like a good deal to me for zero mana
If a card like Smoke greatly affects your Craterhoof Behemoth deck, think about including a card like Boseiju, Who Endures as support
Looking at one of the games most natural colors: Green