At sub-light speeds, travel to other planets/habitable systems is highly restricted, but possibly doable with a few advancements in our current technology maybe...
Say we developed the technology to find for certain habitable planets first, and then let's say we found one, or a few, and let's say around 50 light years away, etc, then let's also say we could travel at 1/4 light speed, and then also maybe the ability to put human beings into cyro-sleep, etc, and then we would probably also need it to all be automatic and run by computer, etc, and maybe a very advanced computer or AI to pilot it, etc, well, then we could probably launch something at least, but it would take 200 years to get there, but if we could do something maybe like that at least, even if humans destroyed themselves here, at least the human race would have another chance at continuing to go on, and the whole race would maybe not become extinct maybe, etc...
God Bless!