You are the one who brought up character design and lighting.
Here are some of the components of animation.>character design
The more detailed the design is, the harder it is to animate and the better it looks. Anime emphasizes detailed designs, i.e. detailed drawings, while American animation does not (stuff like Steven Universe is as dead simple as it gets). With detailed designs you also have to take into account the physicality of the clothes, so that they appear to be physical objects separate from the character and move realistically. As opposed to just being painted on. Detailed hair of course also poses its challenges.>animation
Some things are a lot harder to animate than others. A basic walk cycle is easy compared to complex fight choreography or dancing (and even walking can be difficult if you get creative with the camera work). Effects animation like debris, explosions and smoke can also be very difficult, as can anatomically detailed animation (e.g. https://sakuga.yshi.org/post/show/4283/
). With movement you also have to consider (depending on the animation style, anyway), realistic weight and momentum and energy transfer.>camera work
What we see again and again in American animation is stage or theatre-like animation where the characters just move left and right on the screen. This is rather easy (and really boring) compared to odd camera angles, rapid changes in angles, low angles, foreshortening, three-dimensional camera movement (with or without animated scenery), and characters moving through the scene in a three-dimensional way.https://www.youtube.com/watch?v=rR1cMPnMcaYhttp://www.dailymotion.com/video/x28l37_you-re-under-arrest-op_funhttps://www.youtube.com/watch?v=MU0i6OLmPj4https://www.youtube.com/watch?v=qsv5pUKHRCAhttps://sakuga.yshi.org/post/show/17747/>lighting and shading
Adds to the quality and realism of the animation and characters, and of course makes it more difficult and time-consuming to draw.