I agree that JIRA is probably not what you want as your user-facing bug tracker, but Bugzilla seems significantly less complicated, and the github issue tracker is easier still (though I think it is over-simplified for a user-facing bug tracker).
Someone above mentioned wanting free form bug trackers, but this runs into the problem of bad bug reports. You want bug reports that you can reproduce, or at least some artifacts such as crash dumps or stack traces that give you something to analyze. Short of that you're left guessing about what the problem is. Hence, bug trackers tend to ask people for more information up front so that there is less back and forth.
I wrote about how open source project bug trackers aren't as inviting as they might be a few months ago: https://www.benburwell.com/posts/open-bug-tracking-empowers-....