You send a swarm of probes using laser propulsion and they land on the destination planet and self assemble communication and then you beam humans over as electromagnetic radiation because that's a thing you can do if you can put the human mind into an electronic format. You can hit fractional light speed light like that because the probes are small, the tricky part is the landing, but I suspect we can make that work using gravity, light energy from the star in the new solar system, atmosphere and the fact that it doesn't have to land super soft.. but you do have to slow down a lot with minimal power, which is tricky but should be doable. It's all about going super low mass on everything you send through space.

You don't need to carry the humans in the ship and you can lose some probes along the way, you just need one to get there and start a harvesting and assembly process to build the basic infrastructure.

Then you can send humans at the speed of light and clone them at the destination and all you risked was tiny probes accelerated by ground or space based lasers aka the lowest mass possible to keep speeds high and complexity low.