Idea Summary
Back arrow on the Breadcrumb Bar as part of the Universal Theme.
Use Case User Navigation.
Preferred Solution (Optional) Using the Breadcrumb data, simply keep an Arrow button there that goes back to parent.
I'm not sure that in this age of web development that such a button is expected by users or even required? On desktop you always have that back arrow in the browser, and in mobile, browsers support swiping back.. one exception I can think of is in a desktop PWA, and in fact, this APEX Ideas app demonstrates - which is why we have a “< Home” link at the top - but this is a customized page template.
But, in the breadcrumb bar? I think if we supported that easily it'd be akin to a bad practice or bad design pattern perhaps.