I’m not saying that they would have defeated the Spanisn in the long-term but conquering and permanently occupying all the native states in Central America would have significantly more expensive for the Spanish. Without the diseases I think it’s not unlikely the Spanish empire in the new world would have more closely resembled British India i.e. a bunch of semi independent states and directly controlled areas with the majority of population still preserving their culture and language. And in general European colonization would of the new world would have been more similar to what happened in the rest of Asia and Africa.