Rashbam explains in his introduction to Chumash that chazal did not engage in peshat, only in derash.
Therefore, he says, he is not arguing with chazal when he explains pasukim differently.
For he is explaining according to peshat and they are explaining according to derash. To repeat, anything that appears in chazal is by definition derash. Nothing from chazal is peshat.
And when he disagrees with Rashi, which is the majority of his peirush on Chumash, it is for that reason as well. Not that Rashi’s peirush is invalid, but that it is derash, not peshat.
Same with the other mefarshim who disagree with Rashi, that Rashi is derash, not peshat.