You don't need bronze or iron for jaguars. Just spam them from a barracks with CR1 until you get a win agains an archer, hide them in the forest with a warrior and wait for it to heal, you get CR2 jags then. Once you take the nearest capital move north to get horses conquering on the way.
This is a fun challenge, still haven't won yet but I am 1 turn away from cavalry and another 1 after that from grenadiers since I lightbulbed chemistry, plus I traded for replaceable parts so only a few turns away from rifles after that. I have so many cities and used universal suffrage (from capturing pyramids) to buy banks in all my commerce cities so I am making a profit at 60% research now, shouldn't be long now but still very slow compared to other people I expect.