Any sentient species in the galaxy can sum up the major transportation systems by one word: resourceful. When you can’t use one method for space travel, others are available, for a price.
Simpler species, like the humans of Terra Firma, could assume there is one method just by calculating the vast distances between worlds, their current physics mathematics, their technology, and scores of science fiction stories most species fall asleep over. And stick with it.
Such narrow-minded reality thinking is not tolerated. It’s best to remind them what’s available, starting with the cheapest.
Cryogenics is still active, as intravenous fluid engineered to create an artificial state of hibernation, or the cryo tube for full-body deep freeze. Scores of people in one ship traveling in deep space on a designated course. Although this is the cheapest and is limited to traveling between planets, this is frowned upon when associated with alleged smuggling, kidnappings, slavery, non-sa