Are you talking about some specific type of paradox? I don’t think anything you’ve said would preclude the existence of one or any number of paradoxes. Maybe I’ve missed something. As to the rest of it, maybe time isn’t linear maybe it’s a Mobius strip or something. Perhaps if time travel was possible or is possible now in somebody’s present maybe everything is in constant flux, or each change creates a new, separate time line that exist right next to it, in another similar universe or maybe time travel is just highly regulated with extremely harsh penalties for screwing stuff or maybe someone created some kind of fail that keeps people from committing antepatricide or whatever you might call it. Who the hell knows? Anyway, somebody had to be the first one to answer this question. A shame there isn’t time travel because I have premonition that I will have something more interesting or more coherent to say about 1 minute after my 15 minute editing window has expired.