Do vex always exist? If they are part robot, part organic, and utilize the same shared space then they must. For the most part we think the only thing they want is ones and zeros, but they can't survive without the organic radiolaria...so they can't be solely 1-0, they must be organic.
It's just something to think about, question the logic of this game.
-
Hm. I'm gonna say yes based on the following thoughts. First, from the earliest time they're introduced, when Crota was tricked into cutting into their "world," they seem to be as they are now for the most part. My take on that is in the Vex world (or dimension/reality) they are and always have been. If you consider the possibility that these dimensions, maybe all dimensions, run in space and time parallel to one another, then it makes sense that the Vex would appear to transcend time once they deduced the "sword logic" and began worshipping the Darkness, invading other worlds. I think this is also in large part to their nature, a single organism copied an innumerable amount of times, perfect for sharing information across time and space without limit.