Brahmans were not some magical or alien beings. Brahmans were traditionally the most talented and strong charactered people. But due to some natural circumstances, the situation deteriorated and other forms like Buddhism came which weakened Brahmans and lead to chaos. When Brahmans were ruling, there was no problem of evil. But when Buddhism came, people became weak and cowardly, paving way for invasion.
Brahmans were discriminatory but that is because God does not create people equally. Brahmans only discriminated on merit, not on their whims. So, it was in a way, "good discrimination". Only evil is indiscriminate, going against natural creation. Brahmans were never casteist except after islamic invasion whereby the combination of buddhist cowardice and Islamic menace caused a seriously fragmented society and the quality of Brahmans also deteriorated due to continual war and lack of source of knowledge. The root cause of Indian problem is Buddhism which caused severe weakness and cowardice. Brahamns are the reason why anything is left at all.