Here, these phrases do not refer to a specific person but to humans in general, including both males and females. Alternate translation: "their feet ... to them" (See: [[rc://en/ta/man/translate/figs-genericnoun]] and [[rc://en/ta/man/translate/figs-gendernotations]])
The author speaks of humans having control over everything as if they have stepped on everything with their feet. Alternate translation: "You have given them control over everything" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This double negative means that all things will be subject to Christ. Alternate translation: "God made everything subject to them" (See: [[rc://en/ta/man/translate/figs-doublenegatives]])