Good question, but could they perhaps travel in some other way, dimensionally for instance?
Yes,
I am a big believer of inter dimensional travel.
I assume in inter dimensional travel, points in time are not important since the humanoids are traveling at our speed.
A point in time would be irrelevant in dimensional travel as one would just have to go through a portal.
Consider this; anything outside of one's lightcone is interdimensional travel, in a sense. Any superluminal communication (including, obviously, physical travel) breaks causality. That's not to say it automatically leads to paradoxes, but it has the potential to, if we assume a single, four dimensional interconnected spacetime. If you allow for superluminal communication, for example, it's possible for a vessel reacting to an event that's already occurred on Earth to, from its reference frame, warn Earth before it happens. The
Star Trek model of zipping about at warp speed and communicating via subspace with no concern for causality just can't happen, even if those technologies are possible. But, if those techs are possible, it's difficult to know what the results would be.
It's impossible to know whether we could travel faster than light because we don't have an ironclad model of the universe. But, to give some idea of how difficult it might be, this is helpful. Everything is traveling at the speed of light through spacetime, all the time. You think you're going faster when you're in your car on the motorway (freeway)? All you've done is taken a little bit of your journey through time and redirected it through space. You think the speed light travels is fast? It's just that the light is only traveling through space, not through time at all. Everything is always traveling through spacetime at the same speed. It's the speed of causality. So, it's not just a matter of traveling 'faster than light'. With all our technology, we've never managed to change our velocity
at all, we've only managed to change our direction in spacetime. Left, right, nose up, a little more through space and less through time, now quickly less through space and more through time... I said apply the breaks quick! Obviously moving faster than light involves not only traveling through space faster than light does, but still traveling through time at least a bit or you won't be able to control your spacecraft, so it means for the first time moving through spacetime at a different velocity than everything everywhere has always done as far as we know.
But, what might it be like if we travel superluminally? I'm not convinced it's a good idea. One way around emerging paradoxes is if there are numerous versions of reality, and if you make this faster than causality leap, the world from which you came begins to expand into a wave function of possibilities, which will collapse into a random world once you 'drop out of warp'. You'll have jumped to a new 'dimension', of sorts, but randomly, with no hope of happening to return to your original dimension. Traveling backwards through time might be the same. Perhaps you'll create a new parallel timeline, perhaps the 'past' you arrive at isn't that of the world you left at all. Perhaps there's no way to get back to your 'original' present. If the flying disks come from a future, it might not be our future, and they might not be visiting their past. So, I see 'time-travel' and 'superluminal travel' as forms of 'interdimensional travel', probably involving the same technologies, and the same problems of never knowing which world one will arrive at.