First I think that's important look for the beginning of the myth of Yellow Emperor, based in literary evidences.
He's referenced as an "divine hero" by Birell in the book Chinese Mythology: An Introduction (1). Later, she says:
This concept [axis mundi] has been particularly rewarding in discussing symbolic opposites, such as Ch'ih Yu and the Yellow Emperor, or the failed hero, Kun, and his successgul son, the hero Yu the Great. [..] One of the seminal theories of Georges Dumézil on dual sovereignty or joint rule (1940) has been helpful in recognizing and elucidating the complex myth of the divine (half-)brothers, the Yellow Emperor and the Flame Emperor, who each ruled half of the world but who later fought for total supremacy
Birell continues:
The god called the Yellow Emperor played a minor role in the early tradition, but he gradually acquired a complex biography, an elaborate genealogy, and a cycle of folklorist legends that gave him an exalted status in the divine pantheon. Although later tradition made him the supreme deity of the Taoist pantheon, when philosophical Taoism had acquired a more religious coloration and was espoused by imperial rulers, and although traditional histories have presented this god as the pacific culture bearer, the early tradition clearly shows that the Yellow Emperor (HUang Ti) is first and foremost a warrior-god who successfully fought against a series of enemies - the Flame Emperor, Ch'ih Yu the god K'uei. For the Han historian Ssu-ma Ch'ien, the Yellow Emperor symbolized the fountainhead of Chinese culture and civilization.
Has a many of stories about the Yellow Emperor, such as "The battle between the Yellow Emperor and the Flame Emperor", in which each of them reigned under one part of the world and fought for the total supremacy. And the battle between Ch'ih Yu, the god of war attacks the Yellow Emperor, from The Classic of Mountains and Seas
About what kind of god he was, Cho-yun Hsu (2), says:
The Yellow Emperor is the ruler of mankind, and he bears the responsibility for overseeing the world and giving birth to culture. He is at the same time a deity and a controller of deities, able to dispatch gods and demons on his missions and with the superhuman powers calling the winds and summoning the rain.
For McDermott (3), the Yellow Emperor
had more than merely thematic ties to the sacrifices. In the Shi ji, a major impetus to Emperor Wu's decision to perform the sacrifices was the discovery of an inscribed vessel supposedly cast by the Yellow Emperor pior to his performance of the feng and shan, which resulted in his ascent to Heaven as an imortal. It stated that the Yellow Emperor alone amongst the seventy-two rulers who had attempted the sacrifices had actually completed them.
In Warring States and Han mythology the Yellow Emperor was a god of war and storm who originated in the states of Qi and Qin, as well as a demon queller who figured in the travel sacrifice, the funeral procession, and the ritual of exorcism. He was also a major divinity of the imortality cults and the medical schools of the period. Thus he embodied many of the aspects of the feng and shan sacrifices: conquest, procession, immortality, and elements of mountain cult.
The hierarchy of the spirit realm was ruled by a supreme deity known variously as the Celestial Thearch (or "Emperor"), the Yellow Thearch, or the Yellow God Northern Dipper. The Northern Dipper was both the celestial palace of the Yellow Emperor and his spirit progenitor, and Ban Gu identified the Yellow God with the Yellow Emperor, so it is virtually certain that all three names referred to a single divinity. This god and his officials dwelt in four constellatons from which they observed human conduct and distributed rewards and punishments.
Through the texts of Taoism and the mythology of Qi and Qin, it is understood that the Yellow Emperor was a supreme deity of the pantheon of gods.
Many sources cite that he created the friction technique to generate fire and passed it on to humans. This and other inventions are attributed to the god.
Finally, on the humanity and ascent of the Yellow Emperor, for Allan and Phillips (4), the Yellow Emperor is
the China's greatest mythical sovereign and the legendary ancestor of the Chinese people. The tale comes from Seven Tome from the Cloudy Shelf by the Daoist Wang Chuan of the Tang dynasty (618-906). By that time the Yellow Emperor, known as Huang Di, had been revered as the supreme Chinese deity for many centuries. Earlier, in his Historical Records, the Han historian Sima Qian (c. 145-c.86 bce) had traced the history of Chinese civilization and established the Yellow Emperor as the great forefather and propagator of Chinese culture.
After defeating Yan Di, Huang Di became chief of the gods, assuming overall authority as God of the Center. Was also said to have been the first ruler to establish and organize religious ceremony in China. According to some accounts, Huang Di, or Xian Yuan, was given a pull that granted immortality by Tai Yi Huang Ren, the spirit of a mountain in Shichuan Province. Huang Di visited the peak with Chi Jiang Ziyou, who stayed on to serve the mountain god, surviving on the flowers that grew on the gently sloping sides of the peak and gradually losing his Earthly body in favor of a heavenly one.
References:
(1) BIRRELL, Anne. Chinese Mythology: An Introduction. 1 ed.: JHU Press, 1999.
(2) HSU, Cho-yun. China: A New Cultural History. Columbia University Press, 2012.
(3) MCDERMOTT, Joseph P.. State and Court Ritual in China. Cambridge University, 1999.
(4) ALLAN, Tony; PHILLIPS, Charles. Ancient China's Myths and Beliefs. The Rosen Publishing Group, 2011.
