My child can do many things alone, but children with intellectual disabilities inevitably get helped a lot. How can I raise a child who stays endearing and good at being helped even as an adult?

A wonderful perspective. In common: being able to rely on others and to warm up a room are very important strengths for life and work as an adult. As a foundation for raising this: (1) build the experience of always responding when they manage to say "help me," (2) make greetings and thanks part of daily life in the form the child can (words, signs, a smile), (3) create places to share strengths and likes with others, and (4) have adults affirm the child's own way of being positively. What the family decides: what way of being to cherish is fine to differ by family. Being good at relying on others, not just doing things alone, is a fine life skill too.