when you shrink pictures down they tend to become unobvious, all the original pictures were quite good
about the black and white, i did that on purpose, those are actually some of my favourites because they're easy to discern (and i did it globally across tier 1 units), and their simplicity expounds their early appearance.
the ones im least happy about are some of the higher quality pictures like marksmen, flurry, knight, and horsearcher because shrunk down theyre hard to work out. but it was hard to find good pictures for them (finding specific pictures like a dark elf on a horse, or finding a sneaking archer, were quite difficult). i havent been too worried because theres already many pictures like that ingame, so many i have no idea about heh. vanilla civ gets around this mostly by making things cartoonish, i did that for the middletier units, but thought id follow the trend of cryptic pictures for the endline buttons. so it follows a nice pattern of black&white for low, cartoonish for mid, and cryptic complex for high.
i will relook at things once i make some more units, but the current setup works out for me.