A quick history on the disparity between relative ranks of Captain in the land and naval forces (some details glossed over):
In the beginning a military force, a company, was commanded by its captain (usually a ranking noble or gentleman at least), assisted by lieutenants and sergeants.
Also in the beginning – before there were formal navies – a ship was commanded by its master (probably some poor schlub), assisted by his mates.
Periodically, there would be cause to embark a military force upon a ship. The maritime functioning of the ship would be overseen by the master, the only competent mariner, but the overall command would be in the captain, an officer and gentleman.
Once more permanant navies were being establish, there was a officer captain (and lieutenants) put in command of the ship, and the ship’s company, though there was the technician master kept for his navigational expertise.
Vaguely around the same time, military companies were organized into larger formations, with groups of companies organized into regiments led by colonels (leader of a “column” of companies), assisted by lieutenant colonels and sergeants major (a rank later abbreviated as major). Even bigger formations were lead by a colonel general (later abbreviated to general), lieutenant [colonel]generals, and [sergeant] major generals.
Once naval ships came to be very big and important, the captains commanding the largest ships were determined to be of approximately equal rank to land force colonels. It was also realized that some of the smaller ships didn’t need a commanding officer with quite the rank and dignity of a full captain, so the rank commander came about for those in charge of smaller ships.
There were some even smaller vessels that could be overseen by a mere lieutenant. Originally, there was no distinction between a lieutenant commanding a small vessel and a lieutenant serving under a captain or commander on a larger ship, but eventually, after enough folks started signing their letters, “Lieutenant, commanding,” the rank of lieutenant commander came about. On large ships, with multiple lieutenants, one would be designated the first lieutenant, another the second lieutenant, another the third lieutenant, down until they ran out of lieutenants. The master would rank somewhere in among the various lieutenants. Once the age of sail passed into steam, the post of master sort of merged into the lieutenant ranks, so now we have lieutenant ranks in the of lieutenant commander, lieutenant, lieutenant junior grade and ensign (called sub-lieutenant in the British navy).
Essentially what in the land forces became the officers of the smallest full military units, the captain and his lieutenants, also became the officers of the smallest full naval units, the captain and his lieutenants. However, because the size of a ship was so much large than that of a military company, the relative ranks of their captains diverged.
As to the OP’s question, based on this history, it would make sense for space “ship” units to be based on the naval rank structures, assuming that the ships would be substantial enough to be commanded by someone at or near a naval captain/colonel level.