Trust the past implies trusting those you know and grew up with and thus those most like you, as in your in-group. It also means you may overlook their mistakes

Trust the past implies trusting those you know and grew up with and thus those most like you, as in your in-group. It also means you may overlook their mistakes and crimes because you may trust they're doing the right thing. Moving forward with caution doesn't mean you absolutely don't trust others but they are the out-group, if we assume there are two groups here. Those others won't get the same benefit of the doubt as your in-group and thus any mistake they make will be magnified (in relative terms).