People literally make them look as young and as small as possible.
Again, a small person doesn't automatically make them young. A person with a young appearance isn't always as young as they look. I know many people who even now look like they're in high school well into their 30's and even I looked about 16 until my mid 20's. You can't assume someone's age based on appearance. The only one here I see making the characters out to be children is you. There's no way to make them look any older or younger. The face is just the same face no matter what.
And yes, that does mean that characters that look young but are 1000 years old, really are just young looking old people. More importantly, they're not real. None of this is real, so don't get offended, and just ignore it if it bothers you so much.
And there lies the problem.
Ignoring is the same as saying it doesn't exist or at least pretending it doesn't. That doesn't address any issues regardless of the side you're on. If people don't bump heads then we end up with a hivemind with an awful echo chamber.
Clearly things aren't fine when cultures are so vastly different. This is why localization exist.