I have four reasons why we would never see aliens from another star.
1) The cosmos is filled with radiation and any long journey through space would be hazardous.
2) If you travelled through space you would eventually collide with a meteorite.
3) Space ships are small and a long journey time would be difficult to endure.
4) Anyone on a space station for over a year suffers from muscle weakness and bone dystrophy.
In response to each point.
1. There should be no difficulty in providing appropriate shielding for an interstellar voyage.
2. Our present spacecraft are constantly colliding with micro-meteorites, but are designed to tolerate that. Very large meteorites could be detected early and avoided. Medium sized meteorites could be zapped by powerful lasers. Small meteorites could be absorbed in the body of the craft.
3. One would not attempt an interstellar voyage on a small ship. You seem to be thinking in terms of present day technology. I'm envisaging the technology available as the equivalent of Earth tech. in a couple of centuries, or four or five millenia from now.
4. This can be dealt with by one of genetic engineering, long term evolution of a sub-set of humans born and raised in space, medical intervention, or by rotating a portion of the craft to simulate gravity.
All of these are best dealt with by finding a suitable asteroid, burrowing into it to create living space and locations for all engines and equipment.
Of course, there are likely much more elegant methods available to aliens who are not a couple of millenia ahead of us, but twenty or thirty million years more advanced. Bottom line, I don't think your objections hold up.