Hello,
Blanco did not have the breadcrumbs image option. It had shop promo banner option only.
XStore also has this option in Theme Options > Shop > Product page layout > Shop Page Banner content + Shop Page Banner position. But this content will be displayed for the shop page only and not for the product category page. If you want to add any banner or text for the product category before the products use the description area.
Category thumbnails are the images of the product category that you see if use the category element on the simple page, for example, http://prntscr.com/m4thmc
Heading image is the background image for the breadcrumbs, it may look nice if you use the larger paddings for the breadcrumbs and want to accent the page title, for example, https://xstore.8theme.com/demos/cocktails/instructions/ or https://xstore.8theme.com/demos/flowers/blog/
If you just need to add the banner for the category use category description field.
Regards