Black powder fouling is, and always has been, nearly 100 percent soluble in water. It is not soluble in oil or grease.
I trust the old timers knew this, and used primarily water to clean their black powder arms.
Sperm Whale Oil was readily available in the 19th century. It's a very good lubricant, so it was used to lubricate moving parts.
Bear grease wasn't readily available to everyone, but whale oil, water and lye soap were.
I live in the remote Utah desert. There isn't a bear within 100-200 miles of me.
In the 19th century and early 20th century, the distribution of goods wasn't as efficient as today. The last stagecoach robbery was in 1916 in Jarbidge, Nevada. Yep, they were still using stagecoaches in 1916, to carry mail, passengers, payroll and minor freight to remote areas. Jarbidge remains a very remote town, often inaccessible with modern vehicles because of snow or mud.
I doubt there's a bear within 100 miles of Jarbidge.
We'll probably never satisfactorily know what the old timers used to clean, lubricate and preserve their black powder firearms.
Water, or water with additives, is a given. But aside from that, people used what was available. Colt's suggested clean water in its vintage instructions, as I recall.
I've used hot, soapy water for more than 40 years, to clean black powder revolvers and rifles. After cleaning, I rinse their bores with hot water, and wipe them dry while the metal was still heated. When dry, and still warm, I coat with olive oil. Never had any rust appear.
Did they clean their firearms meticulously all the time? It's doubtful, and the condition of original black powder guns today reflects how poorly they were maintained.
It wasn't abuse, but lack of opportunity to give them a good cleaning. They were kept loaded -- and handy -- often for weeks or months.
I don't think anyone can proclaim that this or that was used. I suspect a lot of ad hoc cleaners and lubricants were used.
Incidentally, I've never seen a vintage cap and ball revolver with any trace amounts of lubricant. All I've seen have been drier than Hell's saloon. Whatever the old timers used, it sure didn't last long.