#prev most of these chinese languages are spoken by ethnically han chinese

[999-roses]

These represent the main 7 language groups (+a few dominant languages within the groups) that are currently spoken in China and fall under the Chinese (Sinitic) language family.

Frequently, all languages under the Sinitic umbrella are colloquially translated as "dialects" - a common reason being that they mostly* share a writing system (汉字 hanzi). However, linguistically speaking, they are not dialects, as that requires speakers of different dialects to understand each other with not too much difficulty (mutual intelligibility). (To add to the confusion, regional variation within the local languages commonly split along urban--suburban/rural dialects. Furthermore, there are regional dialects of Mandarin Chinese, as it is the lingua franca of the nation.) Languages in the same language group typically are not mutually intelligible with each other as they are still different languages. For a more clear example: Shanghainese is a dialect of Northern Wu, a language of the Wu language group, which belongs to the Sinitic (or Chinese) language family. Shanghainese is mostly intelligible to other speakers of Northern Wu, has varied intelligibility %s to speakers of other Wu languages, and very low mutual intelligibility with speakers of other Sinitic languages like Mandarin.

The linguistic geography of China is incredibly diverse. For the most dominant language FAMILIES (eg not just the Sinitic languages) spoken here's a map pulled from wikipedia:

Additionally, many minority languages have state support and are taught in schools in regions where they are locally spoken.

* It's a bit complicated to explain... tldr: So, to say that all Sinitic languages share the same writing system is kind of true, but also is not true.

Historically speaking much of the sinosphere or areas influenced by Chinese culture used Literary or Classic Chinese, which was more or less codified when people still spoke Old Chinese. Because of the predominantly logographic nature of 汉字 hanzi, variations in pronunciations of words between languages didn't pose a big issue in continuing to use and understand Literary Chinese.

However, Literary Chinese did not undergo natural linguistic evolution the way that Old Chinese -> Middle Chinese & diversified Chinese languages, so Literary Chinese largely preserves the grammar of Old Chinese and also -where it can- preserves the scarcity of mutlisyllabic words (that are now prevalent in most currently spoken forms of Chinese). The tradition of reading aloud works written in Literary Chinese is/was still done, but more along the lines of memorization and continued use in written form, and not along the lines of reviving its use as a spoken language.

There were several literary movements (old as 1300s Yuan dynasty and as recent as 1920s) that sought to use vernacular instead of Literary Chinese, initially for plays and stories intended to be spoken instead of only read. The later movements, such as the 白话文 baihuawen movement, also had increased literacy as one of its goals, because Literary Chinese was hard to learn for non-scholars/ordinary people. It took place before Standardized Mandarin was chosen as lingua franca and also before Simplified Chinese (writing system - a 汉字 hanzi variety) was compiled. The preferred dialect chosen by many of the writers was not Mandarin, but Jianghuai, also known as "Lower Yangtze Mandarin 下江官话" which was the lingua franca of Ming and Qing dynasty China. "Mandarin" in this sense is the transferred from Portuguese (Portugal had oldest European colonial outpost in Chinese territory - Macau) translation of 官 "(government) official".

Related to baihuawen movement is the development of 汉字 hanzi characters specifically used in Cantonese and Hokkien, to better reflect parts of speech variants found in their respective languages that aren't in the lexicons of other Sinitic languages. Also because of the nature of linguistic evolution, some Sinitic languages preserve older (archaic) forms from parent languages, and as such, some of them use "archaic" characters for written vernacular. Others come up with new/separate characters

Map of Chinese languages (Varieties of Chinese) in China and Taiwan, excluding Chinese counties where a Chinese language is not spoken by more than 50% of the population at home.