Baby Yoda meets Baby Groot

The Original Ravagers featured during final moments of Guardians of the Galaxy Vol. 2 (and during one of the many post-credit scenes) were actually select characters from Marvel Comics lore: The Original Guardians of the Galaxy. By "Original," we mean that they were the first iteration of the Guardians of the Galaxy team, who appeared in the first installment of the comic series in 1969, throughout the '70s. It's clear that in the Marvel Cinematic Universe, the original Guardians team either disbanded or evolved into the larger group that is The Ravagers. The members of that original team were never quite as popular as the revamped version with Star-Lord and company - which is why it's perfectly understandable if audience members (even longtime Marvel Comics readers) didn't get it, in the moment.