Yes, it's possible for humans to colonize "space" --if not a planet-- right now. If fuel considerations are eliminated, all that matters is life support. Well, that's still a tall order because it would require energy for food production, medical treatment, and simple repairs necessary for maintaining the environment. And, we'd have to find out what the inevitable effects of cosmic radiation would have on our dna.
Ya know, right now, it'd be possible to create a spacecraft that could reach half the speed of light or faster. All it takes is enough hydrogen bombs. It'd mean sequentially detonating nukes in space. Well, ok, stopping would still be a problem. Newton's laws are a b..ch.
It's all theoretically practicable to move humans to the outskirts of the solar system in a lifetime.
If evolutionary development to intelligent life with technology is inevitable, then we can seed the galaxy with life today. We don't have to send humans anywhere to save the species --if that's the operating premise. We can send bacteria. Of course, we can't really know whether those bacteria will evolve into dinosaurs, and that a meteor strike will kill them off so that little mammals could emerge to dominate. Lots of big and little accidents needed, but we know it ain't impossible.
I'm always struck by the argument of inevitability. The universe is so vast that people say there must be somewhere in it where the exact same things have occurred. So, there must be a RSF somewhere else in the universe, and some Steve writing this at exactly the same time I am. Ok, I get the idea of quantum entanglement. But, I'd go more with the idea that this may be an inter-dimensional phenomenon. I.e., there's only one me in this dimension (or time space continuum). However, my point is that why --in an "infinite" universe-- we (or I) would have only one twin? Why not 50?
Sorry for the sidetrack. I think we could save the species already, but we're too greedy and self-centered. Technology offers solutions, but it's far more likely that we'll use it to destroy the best place in the universe for us or each other. What may keep us here is simply human nature. It's how we can imagine Klingons and Borgs. It's why there are weapons on all our movie space ships. My favorite alien film is "The Day the Earth Stood Still." It might take some aliens to force humans to cooperate with each other --for the sake of the other life on the planet, and maybe even for life in general.
So, as in the second video, maybe there are aliens who are trying to hold us back as well as help us? Vulcans might conclude that eradicating us was logical. Klingons would see us as weaklings. The Borg would say "assimilate or die" and "resistance is futile." They all sound extreme until we recognize that they are just reflections of human societies. Otoh, maybe the only highly technological societies that survive are the ones that manage to control their environment to the point where it is a self-sustaining paradise that is unnecessary to leave.
"A man is rich when he has time and freewill. How he chooses to invest both will determine the return on his investment."