Gautam Buddha was NOT Against Brahmins and Caste

Buddha did not even intend to create a separate religion.

For example- Buddha Explains 5 types of Brahmins and clearly says that "Pure descent" is a necessary Criteria for a person to be Brahmin and Brahmins are equal to Gods*

This was one category out of 5.

And if anyone claims that's not Buddha's own beliefs but he was just telling what beliefs of Brahmins are, not that's wrong because after that it is said-

"Gotama has cleared dhamma, he revealed the truth"

That means this was the truthh

Hence Buddha did not Intend to remove or oppose Varna system, he only wanted people to follow proper Dharma as per his understanding.

Later Buddhists got into conflicts with Brahmins after death of Buddha.

Because Buddha did not want to harm Brahmins (Majjhmika Nikay)-

Source - Anguttara Nikaya 5.192 (Dona)

Majjhmika Nikay 95 (Chanki)