Humans

Humans are living creatures that exist in areas of the world beyond the Smurf Village, mostly in villages of their own. They are usually within 6 feet tall, making them appear to be giants in comparison with Smurfs. Unlike Smurfs, they reproduce physically and tend to age in decades what would take Smurfs centuries to age, with an average lifespan of 70 years. There are also as many females as there are males among human communities. Like Smurfs, human male adults also grow and wear beards.

Despite the benevolent nature of some of the humans the Smurfs have encountered, humans tend to be spoken of rather disparagingly by Papa Smurf due to the selfish and violent nature that lies deep within the hearts of humans, and he often warns his little Smurfs not to act like them.

From the Smurfs Wiki
It is uncertain when the Smurfs first encountered humans, though it is probably around 10 years prior to their present-day adventures that they first encountered Gargamel the evil wizard (as was revealed in "Gargamel's Time Trip"). In the "non-canonical" Smurf story "The Smurfs And The Magic Flute", their first encounter with humans was with Sir Johan and Peewit, who were searching for the magic flute that Matthew McCreep had stolen and used to commit robberies. Grandpa Smurf had also encountered various humans during his 500-year journey to find the purest sources of the four primal elements to restore the power of the Long Life Stone.

In the 2011 Smurfs movie, the Smurfs came across two humans, Patrick and Grace Winslow, in modern-age New York City for help in reopening the portal in Central Park so that they could return to their own place in time. The other humans in that place in time either ignored their presence or, as in the case of the Smurfs visiting the FAO Schwarz toy store, assumed that they were animatronic toys. The Smurfs also discover that a human named Peyo (who in the real world is actually their creator) has documented their legend for future generations, likening them to leprechauns who are supposed to give whoever they visit good luck.