and sorry, but how is being descended from aliens insulting? I don't like that episode either, but I don't get why being descended from aliens is insulting
First Europeans, then the US Government used the belief that American Indians were not fully human as justification for genocide.
"Tattoo" posits that American Indians lacked speech (unlike other humans) and needed additional alien DNA in order to surivive and thrive.
In other words, we were the stupid humans. Too stupid to develop language without an injection of additional alien DNA.
ETA: This isn't even taking into account the idiocy of finding a tribe of RFA Indians in the Central American rainforest.
Don't see any other humans in Star Trek sporting forehead ridges...