Okay... What am I not getting about CG?

95Range 88Mage 87Def. I have 55ish regular kills and 0 corrupted kills. I can basically sleep through the regular gauntlet. I only do T1 prep, with perfect staff and bow, 3 pots, and the rest fish. Prep is no issue for cg either as I'm comfortably getting to hunleff with 1 min left most of the time. I just cant kill the corrupted hunleff. I usually dont take tile damage, I might eat 1 or 2 tornados the entire time, I dont hit off prayer and I dont get hit off prayer. I swear in a 4 minute fight im making like 1 mistake maybe, maybe less, per minute. My very first attempt I guess I got lucky and got it to 16 hp. Ever since I cant even get it below 100, usually dying around 250. Just totally out of supplies. And I feel like I do a pretty good job at hitting and running too while avoiding specials. I just dont have the dps it feels like but clearly people with worse stats than me do it all the time. Is something just not clicking even though regular feels so easy for me? I dont get this shit and its frustrating.

Edit: I’m not trying to say I’m playing perfect and the game is broken. Obviously I can improve everything I’m doing. It’s mainly just the gap between regular and corrupted seems massive and since I’m never getting chunked out from high hp and it’s all a slow burn it just feels like I’m making less mistakes. Most things in this game will let you know if you mess up by hitting you with a 60. This isn’t so obvious. I’m definitely not as cocky about this as some of the comments are thinking I am lol. That’s why I’m asking for advice not for jagex to fix its broken game.