shoes
靴 centers on footwear: shoes, boots, or any covering worn on the feet.
靴 combines 革 (leather) with 化, which likely contributes the sound and may suggest transformation into footwear. The exact historical development is uncertain.
Leather 革 transformed 化 into something you wear on your feet: shoes.
For カ, imagine a pair of leather shoes that go 'ka-click' with every step: ka -> カ.
shoe; shoes; boots; footwear; footgear
socks; sock; stockings; stocking
leather boots; rubber boots; wellingtons; wellies; long boots; high boots
leather shoes; leather boots
shoe box; shoe shelf
shoe sore; foot blister (caused by shoes)
military shoes; combat boots
hallway slippers; indoor shoes
shoe-making
walking sound; footsteps
straw boots
rubber shoes; rubber boots; wellingtons
ski boots
skates; ice skates
tube sock; tube socks
riding boots
five-toed socks
fairly high shoes; boots
low shoes; shoes
platform shoes; thick-soled shoes