Where the shape comes from
A seated figure with the legs stretched out in front, unlike the kneeling 女: this was the posture of the impersonator who sat in for an ancestor at a sacrifice, and from there the graph came to mean a laid-out body. As a component it simply means "body", which is why it tops 屋, 层, 局, 尾 and 尿.
汉字 filed under 尸
No published character on HSK Guide is filed under this radical yet. 汉字库.