once krishna said

Dalits are the favorite topic of anti hindu and anti national forces to defame India and it's largest practiced culture (hinduism) What if I say it's entirely societal not from scriptures. Check the following verses jātau vyāsastu kaivartyāḥ śvapākyāstu parāśaraḥ | bahvo'nyepi vipratvā prāptā ye pūrvā advijāḥ || The sage Vyasa was born of a fisherwoman, and Sage Parasara was born of a Chandala, many were those who though not previously brahmins attained brahminical status. (M.B. Aranya-parva 312. 106 .) The Mahābhārata also says that it is the qualities of a person that matter - not their birth status. satyam, dānam, kṣamā, śīlam anṛśāsyam tapo ghṛṇā | dṛśyante yatra nāgendra sa brāhmaṇa iti smṛtiḥ || O King of serpents, he in whom are manifest truthfulness, charity, forbearance, good conduct, absence of malice, austerity and compassion is a Brahmana according to the sacred tradition. (M.B. Aranya-parva 180. 20). ...

Firstly the Law Book known as Manusmriti or Manvadharma Shastra was not the work of a single author, there are too many inconsistencies and contradictions. Whatever the original text was there have been hundreds of interpolations over centuries.  It contains laws, regulations and customs pertaining to every walk of life but is primarily meant for the members of the first 3 castes. It is “idealistic’ in that it was never a practical text, nor was it every actually applied in any kingdom in ancient India.  Laws in India were primarily caste-based - each and every caste was autonomous and created their own laws which governed them. It was only major disputes which were brought to the royal court. The Kings were primarily interested in collecting taxes and left the daily legalities to the caste panchayats and their self-governance. There are a large number of different Law Books (Smritis) produced by different Law-givers and used in the many countries and districts o...