Languages change over time, but generally linguists and sociolinguists prefer not to characterize languages in terms of whether they are simple or complex. After a couple of hundred years of comparative research, this has not been found to be a useful metric. Nor do linguists recognize any hierarchy of language in terms of complexity, except that pidgins during the 1st generation are simplified languages of utility, but once they creolize (in the next generation) they become as complex as any other extant tongue.