Despite being a favorite topic of classic science fiction, space travel is not a simple matter.
Even close to the speed of light we could only travel a hundred light years or so due to our short lifespans. It will require several generations to travel any appreciable distance from Earth.
There is a way we could overcome the limit of our short individual existence. Leave our meat behind.
In the near future we will develop robots that can navigate a ship through space. That will eliminate the need for us to transport our bodies. Instead we will send our intelligence, either in the form of artificial intelligences or our own minds uploaded into hardware. Our bodies are encumbrances we really don't need for space travel.
Likewise, we should abandon the idea we'll ever encounter aliens in bodily form. We should expect to encounter alien intelligences, not little gray men.