I found an addon I liked but wanted it to do things a bit differently, so I started and made my own from scratch based on said addon, gave it another name but mentioned in the description where I drew inspiration from, so in a way it also credits the other addon.
Talking about
Honor Queue if you look at the pictures and compare you see they look similar, yet a bit different functionality wise. :P
Anyway, I don't think it will be a issue, especially since the original addon is so "old" now, if you feel so guilty just mention the addon in the description with a link and that should be enough tbh. It's not like you copied his sources, changed some lines and renamed it into your own addon, lol. :P