If the goal is romantic relationship, then I’d say attraction is important. You gave it a fair chance. You tried. Attraction is not even anything you can explain, using hands or mouth to arouse someone is perfectly fine and very common and plenty of short guys have great love life plus he can shave his pits lol But attraction is either there or it’s not regardless of appearances. Sure it can grow. And you tried. It doesn’t seem to grow

It’s better to not drag it. Although honesty is important, I don’t know if that’s needed in these circumstances. I’d not tell him you aren’t attracted to him. Not sure what to say. It’s just not working for you and you wish him the best. I assume you didn’t date him that long so you don’t owe a detailed explanation.