Will there be any other real humans like finn or a human girl that finn could hang out with?

Although it's unknown that the two will meet, there is a gender-flipped version of Finn, Fionna. It's also unknown if their even in the same reality, for the episode planned to introduce Fionna shows a gender flipped version of everyone e.g. Prince Bubblegum= Princess Bubblegum, Cake= Jake, Marsh Lee= Marceline, and Ice Queen= Ice King. The two group of characters must be far apart, because princss bubblegum would've at least mentioned a prince bubblegum if she knew.

I agree with lasar there is an alternet universe sorta. But in coming season three ( starting with heat signature) the sixth episodes título is confirmed as Adventure time with fionna and cake.

LINN THE CHINESE HUMANGIRL COLULD HANG OUT WITH HIM.SEE HOW I REPLACED THE F WITH A l TO MAKE A CHINESE NAME (IM AWSOME)

Hopefully there may be one extra human character for Finn.