Whether the whole time travel experience is treated as kismetic and originally part of a correct overall timeline unknown to the adventurer until the end, is a pretty specific choice and not like a whole other category of time travel model. Nor is it the only scenario in which paradoxes occur. Hell, an origination paradox, the kind you're describing, occurs because of the fact that the adventurer can change their present time, in that type of case, by obscuring the origin of the thing they introduced. They do the same thing in Star Trek 4 when Scotty introduces transparent aluminum or whatever it was.