10mil human eggs or embryos or just genetic material but with bio substrates to print from seems likely to survive a 500 year long deep space journey and far more achieve-able based on current tech.
Send a probe to seed a planet with bacteria etc. Send another to arrive a few 100 years later to seed it with plant life. Work your way up. The last probe arrives and starts printing\gestating humans and offering them educational videos and a safe-ish environment...
"so there are these assholes over near beatlgeuse who haven't figured out ansible communication and therefore think they're alone in the universe. So they send these packets of super aggressive proto organics at every exoplanet their crappy telescopes pick up in hopes of seeding life in the universe, but, in reality, just making life hell for their neighbors. That probe which showed up here twenty years ago? We all have NOSES now, Bob. Do you have any idea how humiliating that is?"
Ha, actually I've never heard of the Enter Chronicles; I just made it up in response to the previous comment advocating for sending bio-trash (or bio-treasure?) all over the place.
Send a probe to seed a planet with bacteria etc. Send another to arrive a few 100 years later to seed it with plant life. Work your way up. The last probe arrives and starts printing\gestating humans and offering them educational videos and a safe-ish environment...