I'm sure we all tried inventing our own languages and alphabets as kids. Most of these probably never went to fruition for obvious reasons. Have we ever found ancient evidence of "draft" language? Take the Latin alphabet as we know it. Each letter has it's own respective shape. Have we ever found evidence of the "discarded" letters that didn't make the cut or were altered versions of what we use now that didn't make it into the final alphabet? This can apply to words as well.
I wouldn't necessarily call them "drafts", so much as just older languages/writing systems that evolved into new ones. In the ancient Mediterranean, for example, there was a lot of interlinguistic mingling that led to cultures sharing linguistic features (including but not limited to alphabets/writing systems). It's turtles languages all the way down, as languages borrow and modify a lot from those around them and the ones that came before them. In fact, as /u/Jemdat_Nasr notes (link upcoming):
It is the common consensus among linguists that there are only four writing systems which were developed independently - that is, with out prior knowledge of writing. These four systems are Sumerian cuneiform, Egyptian hieroglyphs, the oracle bone script [from China], and the Maya script. It is from these four that that the majority of other writing systems have evolved.
Words just kinda fall to the wayside for one reason or another, depending on the needs of the people who speak the language, and leave behind fossils and relics as they get replaced by newer words that are more useful for the next generation. A lot of languages we discuss or encounter in the West are derived from the (proto)-Indo-Europeans of Eurasia several thousand years ago, though there are of course plenty of languages that aren't within that family. The language section of the FAQ features a bunch of responses addressing the evolution of language, but for more some more specifics (and a focus on writing), here are some extra responses:
(Though since you mention people making up languages, I have to give a shout-out to the fact that we do in fact have some data on early versions of invented languages like Esperanto. But that's a separate story, for another time.)