日 rì, a vertical rectangular with a horizontal stroke in the middle, means sun in Chinese. The earliest god created by mankind was the sun god, 日神 rì shén, and as other ancient cultures, ancient Chinese people also had their sun worship and considered the sun as the brightest and most powerful god, before having a multiple-god-system later. Chinese people call themselves 华人 huá rén, bright people, according to a famous historian in China, its origin comes from the ancient sun worship.
日本 rìběn, sun-origin, indicates Japan in Chinese. The name was first recorded in a book of Tang Dynasty around year 670. Japan is at the east of China, thus closer to the sunrise area.
日出而作 rì chū ér zuò, sun-rise-then-work, 日落而息 rì luò ér xī, sun-set-then-rest, an idiom shows that people were following the sun in their daily life. The modern life style could be sometimes the opposite.
日 rì, means also day, daytime in Chinese. 白日 bái rì，white-day, indicates simply the daytime because of the sunlight. 吉日 jí rì，lucky-day, Chinese people choose these days to organise happy events, such as mariage, company opening, etc. 日久见人心 rì jiǔ jiàn rén xīn, days-long-see-people-heart, means we could know the real personality after days long. Let's follow the sun, 日 rì !
Xiao Ling and Lao Long explain more details in the video hereunder.