I think humans, as species are more capable, is some areas and less capable in other. Humans, for example, are absolutely incapable of flying while most birds and many insects can do this naturally. Perhaps the ability to understand alien language is not one of the strong sides of human intellect. That doesn’t mean that human won’t be able to communicate with alien species. This is just mean that alien species that are more apt of understanding alien to them language would learn human languages and thus establish communication. Once such communication will be established, humans will learn from them their methods of pinpointing the alien syntax, grammar, semantics and maybe some other new alien language attributes. At least, I am hopeful.