You can target the first child element with just using CSS selector with jQuery:
$(this).children('img:nth-child(1)');
If you want to target the second child element just change 1 to 2:
$(this).children('img:nth-child(2)');
and so on..
if you want to target more elements, you can use a for loop:
for (i = 1; i <= $(this).children().length; i++) {
let childImg = $(this).children("img:nth-child("+ i +")");
// Do stuff...
}