The girl in this picture doesn't look like a "real" girl but she does look like a human female without visible defects (improperly placed eye/arm) etc.
What do I need to learn to draw and paint such figures which represent humans or animals but aren't be too realistic?
Will learning about the number of bones/muscles and their placements be required here?
I found this picture on internet.
If you want to draw objects (humans, animals, or whatever) that are stylised (i.e. aren't too realistic) you need to learn how to draw them realistically first.
The idea is the same as “learn the rules first in order to know how to break them properly” (sorry for the cliché). You need to understand your subject (what it actually is) in order to reveal it in the way you desire (stylise it). Take a look at what the artists did for the development of the Bambi character.
You can do it the other way round, as people often go for as it brings quick and somewhat satisfactory results, i.e. chose a style and learn to draw this way (like 'how to draw chibi manga girls'). However, understanding the style and not understanding the subject won’t get you far with your art.
