Actually, we venture from the present into the future all the time, 1 second per second, at least within our reference frame.
I get what you mean, though.
The grandfather paradox, though, doesn't preclude travelling into the past. It just precludes the traveller being able to actually change anything in the past that could affect their future, and even that's only true if multiple timelines isn't something on the table of possibilities.
What the ability to time travel may well prove, however, is that time is immutable, meaning that everything from the beginning of time to its end is fixed, which means that free will is an illusion.
Or it could prove something entirely different.
