You don't send people. Nobody wants to spend their entire life on a spaceship. They'd blow their brains out or hop out of the airlock.

You send robots with a life construction kit. When they arrive at their destination, assuming no terraforming required (not a good assumption, but you'd do terraforming first, obviously, if needed), the ship would start building human DNA and fertilizing artificial embryos with it. The embryos would be grown in artificial wombs.

While this is going on, the robots would be building shelters and stuff. When the babies are born, the robots would raise the first generation. Voila: Interstellar expansion of the human race.

None of this is very sci-fi. We can do all of this, to a certain degree. We're probably only decades away from being able to do it all.

Speed wouldn't be a big concern in this case.

Obviously, if terraforming is required, that's a different level of technology required and we're definitely not nearly as close, technologically, on that. But the rest is totally feasible in the next several decades.