Any particular reason she's standing on top white men
A white man - Shiva. They are both Indian/Hindu Gods.
The story goes, after defeating the demon Rakta Beej, she drinks his blood and becomes filled with bloodlust. No one could stop her so Shiva laid down in her path and after stepping on him, she was embarrassed she was so far gone that she did not even recognize her own spouse.
Another explanation:
Shiva, in the Shaivite tradition, is the all pervading eternal primeval consciousness of the universe and beyond. It is upon the ultimate, unchanging time-less reality of Shiva, that Kali (time) does her dance, causing the constant cycles of creation, life and death of all things in the universe. Shiva is the substratum upon which Kali acts. Hence, in this part of the Hindu spiritual traditions, the entire cosmic reality is represented by the dance of Kali (time) upon the changeless all pervading consciousness, Shiva.