How can people create animated images as close to the three-dimensional image?

It actually takes a lot of talent and practice. I'm not talking only of the CGIs of the movie world, you could start by looking at the comic strips or comic magazines of some of the world's greatest creators or writers. You could well see that even though these hasn't passed through photoshop or other programs, they already look good by themselves. Look at this one sample http://www.glasshousegraphics.com/books/ (this is not a referral link). It takes talent really.