If you coul.d change them. For me personally they are really good (much better than civ5 and its infamous anti cavalry unit line ). The only unit really lacking for me is Rifleman unit between Musketman and Infantry, it just feels wrong, the jump is too big for immersion. There's also one unit I'd actually prefer this game to not have, and by this I mean Slinger. Somewhat ahistorical IMO and I fail to understand why is it even here because bow is prehistoric invention and Archer could replace it as instant access unit, with first researchable ranged unit being Composite Bowman. To be honest I could invent some revolutionary unit upgrade lines but they wouldn't be imolemented for civ6 anyway, and I'm speaking about this iteration.