If there is a noun following an adjective, -lig and -ligt or -lige would be chosen according to the article of that noun (e.g. en menneslig kat, et mennesligt dyr, de menneslige elefanter). Please do not forget that if instead of en/et/de (indefinite), definite articles (den/det or any possessive pronoun like my (min/mit/mine) etc.) are used, the plural form (-lige) must be used. In this particular sentence, we don't know the noun, but we know it is plural (DE er) so the plural form -lige is used. Hope this helps!