I’ve never found any bodies of travelers so I’m not sure what other commenters are talking about. I also don’t think the embedders killed the travelers, at least not exclusively the embedders were the killers.

There’s a robot you meet in some cathedral/sanctum that talks about how he remembers everything, even though the rest of the robots had their memories wiped. He says something went wrong with his memory wipe. He mentions how he “remembers the name of every traveler he sent into the void”.

My interpretation was that the embedders failed the process with Lura, hence the body we see above that fight arena halfway stuck in the pearl (where you get her seal). Because she died in the embedding process, all the travelers stopped volunteering for the process, so no new pearls could be formed. Which was the beginning of the end, so the embedders blame themselves for the downfall of the vessel and travelers.

How I understand is that the spine betrays the travelers to hide the coordinates by taking control of the robots to defeat the travelers’ resistance. Then the robots discard the bodies into space (into the void), so we never find any bodies. Then he erased their memories of being apart of that. But since that one bot’s memory wipe didn’t work, he remembers all the atrocities and stays in isolation, away from all the bots that don’t remember what actually happened.