we are not alone, there are many creatures out there waiting for us to visit, and we are billions of light-years away from them
the logic that I take is very simple...
vast space is unlimited, a galaxy is only a small part of space and there are thousands of galaxies in space, in each galaxy there is one planet similar to Earth
is stupid and selfish if we say that only earth has a sentient life on this infinite space
Actually that is the very problem. You say "billions of light-years" but actually, few light-years is such serious a problem, it might make it impossible to ever meet another sentient race.
One of the theories postulates that, by the time you reach any place where such a race existed, they would have been long extinct. Same as them finding us.
The distances of the universe are NOT trivial, in fact they are insane. People can't even start imagining it for real. Closest nearest star (after Sol) is like 4 LY away, and we are not going to travel at the speed of light. A 10% of that is 40 years, meaning a generational ship at best.
But wait, there is more! The simple fact that you are traveling so fast is already taking you to a different time (future) relative to your point of origin. 40 years at 10% the speed of life, on Earth happen to be several more (its possible to do the exact math, but i don't have that ability). Just know that the faster you travel the more years pass for the people not moving with you. Same thing happens to a traveler from another planet coming here...
"Time is relative". This is very, very, very profound. Its not a silly catch phrase, its quite real and dramatic. So for the people on the ship it might be 40 years, for the people on Earth.. 400? And, once you find a place, and settle, this place is already in a different time relative to you as well. Simply because that system is moving at different speed than ours (Sol). And the farther you go, the more dramatic the difference is. Consider that, we are relative far to the edge of our galaxy, and you want to travel towards the center. Well, like a disc spinning, the outer edges move faster than the center, so... Time is relative, remember? fun stuff!
Ten years for a colony in another galaxy might be 1000 years on Earth. A far away race that decides to come here, by the time they reach us we might be extinct, same for us trying to meet them. Even if Seti got a message telling come we are waiting for you, and we embark and take a century reaching some place, it might have passed several more years over there...
The vastness of space, is no child's play. And most sci-fi shows don't depict it properly, maybe to not confuse or make things boring. I think there is a video 3d simulation of how would the "space" look thru the window of a spaceship traveling near or at the speed of light, to debunk common misconceptions, and the answer is very funny: You wouldn't notice anything, as if the ship was full stop. Maybe if you look 90° to the sides you would see very faint moving, but the distances are so vast, looking in all directions while traveling near the speed of like, actually looks pretty much like a wallpaper/bitmap, static and boring, no "white dots" moving AT ALL.
Breaking the speed of life so far is only existing in the realm of imagination. Short of finding or making wormholes, or theoretical engines that need matter/antimatter (
Alcubierre drive?), literally Star Trek stuff. But even with that the other phenomenon persists. You cannot simple go and return to Alpha Centauri and expect the same people you knew to live. Maybe you can meet their descendants...
I know an anime that depicts this, and some sci-fi novels do (with great extent), but i don't know many sci-fi shows or movies that do, I'm probably missing one that does it well. Interstellar kinda did but could have been more explicit. Yes, when you travel fast (or far), you are also taking a one way ticket to the future. This phenomenon is called "
Time Dilation".