If we ever do invent time travel, then surely at some point in that potentially infinite time that time travel was present, then someone will have used time travel to travel back to before this date, thus we would already know that we invent time travel, as we would already have time travel. Am I right?
Alternatively, if we ever did invent time travel and someone was to travel back in time to a date prior to now and the world became aware of our future ability to time travel, this would cause a paradox and the whole timeline from that point until that particular time travel scenario occured would be re-written and this current reality would cease to be.
Third option, we invent time travel and an official law/common courtesy is to "not travel to a time before time travel". Can we honestly expect that the entire human population would adhere to this restriction?
To conclude, we will never invent time travel.