I understand why you feel like that. When you have been rejected enough times, it becomes easy to believe there must be something fundamentally wrong with you. You start looking at other people and wondering why connection seems possible for them, but not for you.
But being rejected and being unlovable are not the same thing.
And comparing yourself to people with disabilities is not really fair to them or to you. They are not getting relationships despite being less worthy or having some greater disadvantage. They are individual people who have found someone they connect with.
You may not be conventionally attractive. I do not know. And I know I certainly am not. But even that would not mean you cannot date or have sex. Attraction is not a scoreboard where the best-looking person automatically wins. People are drawn to humour, presence, kindness, confidence, character, sexuality and the way someone makes them feel.
The hardest part is that when you have already decided nobody could want you, that belief starts entering the room before you do. People feel the defeat, the resentment or the need for them to prove you wrong.
You do not need every woman to find you attractive. You only need to stop treating yourself as rejected before anyone has actually had the chance to choose you.