I challenge you to prove from Vedas that Caste was birth based in hinduism, even manusmiriti 10/65 says caste can be changed according to qualities.
you claim people are not free to choose varna?
The word "Varna" literally means "to choose" https://twitter.com/AfreenFatima136/status/1249407709214117888

Also read this thread if you want to see in detail. https://twitter.com/VedicWisdom1/status/1246288123639631873?s=20