Ignore Twitter trads and read real scholars like Shatavadhani R. Ganesh on Varna in Hinduism.

Quoting him verbatim in this twitter thread. Will plug his pieces at the end.

Before starting, remember this: “varṇa is not a core aspect of Hinduism.”

“It comes under what is called viśeṣa dharma, a set of rules applicable only with limited jurisprudence and are bound by geographical and temporal constraints. It is contextual, not universal, and therefore is a peripheral aspect of our tradition...”

VARNA IN VEDAS

We know for sure that “varṇa has nothing to do with race and ethnicity”. It might have been “a distinction based on occupation or based on the tribes that people belonged to.”

“In the Ṛgveda Saṃhitā, varṇa is not used in the sense of ‘caste’ or ‘class’.....”

“....but rather it means ‘colour’ or ‘light’ in many passages (see RVS 1.73.7, 1.104.2, 2.3.5, 2.34.13, 3.34.5, 4.5.13, 9.97.15, 9.71.8, 10.3.3, and 10.124.7). In some verses, it means ‘form’ or ‘definition’ (see RVS 1.92.10, 1.96.5, 1.113.2, 2.1.12, 2.4.5, 2.5.5, 9.104.4).”

“In some other verses (see RVS 1.179.6, 2.12.4, 3.34.9, 9.65.8, and 9.71.2) the word varṇa is associated with groups of people having fair skin (the āryas) or dark skin (the dāsas or dasyus). But ‘colour’ is “more metaphorical than literal.”

“some of the ṛṣis were dark-coloured, like Kṛṣṇa, Kaṇva, and Vyāsa. Further, some of the āryas had the name ‘dāsa’ as part of their name, like King Sudāsa (RVS 7.18)”

“bright-coloured āryas are those who adhere to dharma while dark-coloured dāsas are those who don’t...”

“..– ‘bright’ symbolizing wisdom and ‘dark’ symbolizing ignorance. We see this in the text itself, where dāsas are described as avrata, ‘not obeying the prescribed rules’ (see RVS 1.51.8, 1.175.3, and 6.14.3) and as akratu, ‘those who don’t perform yajña’ (see RVS 7.6.3).”

“There is a verse (RVS 1.179.6) that has the word varṇau, meaning “two varṇas” and this is used to imply two fundamental dispositions – of desire (kāma) and of penance (tapas)”

“In Ṛgveda Saṃhitā, varṇa is only used in connection with two groups – the āryas and the dāsas.”

“In RVS 7.33.11, Vaśiṣṭha is referred to as a brāhmaṇa, but we know that he wasn’t born a brāhmaṇa (he was the son of the celestial courtesan Urvaśī)”

RVS 10.98.8 speaks of two brothers, Devāpi and Śantanu....younger Śantanu takes over the kingdom, Devāpi becomes a brāhmaṇa

LATER VEDIC PERIOD

“even in the period of the Vedas, during the later part of the Saṃhitā texts and with the advent of the Brāhmaṇa texts, the society became more structured. The distinctions of social class became more prominent....dāsa in later works came to mean ‘servant.’

“Manu’s statement that śūdras were created by the Supreme for the service of the brāhmaṇas (Manusmṛti 8.413)” shows dāsas eventually became shudras

Aitareya Brāhmaṇa 7.29.4 - śūdra is at beck and call of other three varṇa;he can be made to rise at will, can be beaten at will

“In spite of the lowly status given to śūdras in the later texts....they were still considered an important component of the society. For ex, Taittirīya Saṃhitā 5.7.6.3-4 says, “…put glory in our brāhmaṇas, put glory in our kṣatriyas, put glory in our vaiśyas and śūdras.”

“Bṛhadāraṇyaka Upaniṣad 1.4.11-15 mentions that each varṇa is great in its own way. It also divides the gods into four varṇas – Agni is a brāhmaṇa deity, Indra is a kṣatriya deity, Viśvedevas are vaiśya deities, and Pūṣaṇ is a śūdra deity.“

“Although the social classification had started becoming inflexible by the later Vedic period (c. 1500 BCE), we find that those who were really talented attained recognition and came to the forefront, irrespective of their varṇa.”

“The great sage Mahīdāsa Aitareya was a pāraśava (a lower caste; an offspring born to a śūdra woman from a brāhmaṇa man). He was the son of Itarā, a śūdra woman who was married to a sage. He is the seer of the Aitareya Brāhmaṇa, Aitareya Āraṇyaka, and Aitareya Upaniṣad.”

“Kakṣivān, one of the seers of the first book of the Ṛgveda Saṃhitā was the son of sage Dīrghatamas and a servant maid. Chāndogya Upaniṣad 4.4 tells the story of Satyakāma Jābāla, the illegitimate child of a śūdra woman, who goes on to become a great sage.”

“Bṛhadāraṇyaka Upaniṣad 2.1 tells the story of a brāhmaṇa, Bālāki Gārgya, who learns the highest truth from a kṣatriya, Ajātaśatru, the king of Kāśi.”

“similar instances in Śatapatha Brāhmaṇa 11.6.2.5 (King Janaka of Videha instructs sage Yājñavalkya), Chāndogya Upaniṣad 5.3 (Pravāhana Jaivali, the king of the Pāñcālas instructs Śvetaketu), and Chāndogya Upaniṣad 5.11-18 (Aśvapati Kaikeya instructs Āruṇi Uddālaka and others

“These incidents are significant because in the normal course, it was the brāhmaṇa who was the teacher of the highest truths.”

S.R. Ganesh in his article talks at length about

Varṇa in the Purāṇas and the Smṛtis
Evolution of varṇa
Reformation of varṇa
Varṇa and Education
Untouchability

Idea in this thread was to simply introduce the origins of varṇa in Hinduism.

For in-depth study, this two article series on varṇa by S.R.G is a MUST READ

1. http://indiafacts.org/exploring-the-world-of-varna/

2. http://indiafacts.org/a-postscript-to-the-world-of-varṇa/