They might have meant a coletive sense. Fact is, "human" really may have a plural form, depending on the meaning.
As for dancer, he might have meant a class/category.
Anyway, it could be just a music thing, when it comes to music everything is allowed, mauling grammar included.
Now I leave the ball on the experts court. See you around.http://www.grammarly.com/answers/questi ... ns-plural/http://www.goodwordguide.com/dictionary/human#nounhttp://pt.bab.la/dicionario/ingles-portugues/humans
Singulars with collective meaning treated as plural
A number of words like army, company, crowd, fleet, government, majority, mess, number, pack, and party may refer either to a single entity or the members of the set composing it. If the latter meaning is intended, the word (though singular in form) may be treated as if it were a plural, in that it may take a plural verb and be replaced with a plural pronoun: the government are considering their position (alternatively the government is considering its position).