Although it's one of the most popular themes in sci-fi, I don't think humans will ever travel to other star systems, nor do I expect that beings from other star systems will be making the journey from their home system to visit us. Relativity is real, and there is no way around it, so a journey to even the nearest star systems would take millennia. The periodic table is the same everywhere and there is nothing in our home system that couldn't be found in all our neighboring systems, with the exception of one thing: knowledge. We'd like to know about those other systems out there and presumably, they'd like to know about us.

We will soon have advanced enough technology to send artificial intelligence probes to neighboring star systems. Depending on the type of propulsion discovery and advancement make possible, these probes could make the trip between a few decades to a few centuries, and then radio back to earth the information about the newly explored star system.

IIf there is very long-lived technological specea, then they may be suited to taking very long voyages through interstellar space.

Another possibility that could work for humans is a city-sized multigenerational ship. Whether either of these is ever feasible probably depends most on, once again - what sort of propulsion is available. I hold some hope that quantum mechanics will give us a massless push. If this turns out to be the case, and if such a system can work with a power source you can put in a spaceship-city, then maybe there will be families of people traveling between the stars, advancing knowledge. It's a fun dream and it is easier to reason out than believing in gods.