This is not the dumbest explanation of blockchain. The dumbest one is this: a class of students takes a quiz. Instead of the teacher grading it, which would mean the teacher's pet getting lenient treatment, they all pass the quiz to the student on their left to grade. The problem is, no one can figure out the last answer on the quiz, so they're all flipping through the textbook at random to find the answer. They keep passing the quizzes around and eventually, one lucky student flips to the right page, finds the answer, and can grade the quiz on their desk, which go up on the wall at the back of the class for everyone to see, and the lucky student gets a few bonus points for finishing grading. They keep taking these quizzes endlessly with some answers people know and one new answer that no one does. The teacher is the bank, the students are participants in the blockchain, the quizzes are blocks, the questions that everyone knows are transactions that can be checked for validity, the answer that no one knows is the proof of work solution that must be produced (proof of stake would be like a rock paper scissors tournament among the students with already good grades to determine whose grading skills should be trusted), and the wall at the back of the class is launched into outer space travelling away at the speed of light so no one can get to it without breaking the laws of physics.

This is not the dumbest explanation of blockchain. The dumbest one is this: a class of students takes a quiz. Instead of the teacher grading it, which would mean the teacher's pet getting lenient treatment, they all pass the quiz to the student on their left to grade. The problem is, no one can figure out the last answer on the quiz, so they're all flipping through the textbook at random to find the answer. They keep passing the quizzes around and eventually, one lucky student flips to the right page, finds the answer, and can grade the quiz on their desk, which go up on the wall at the back of the class for everyone to see, and the lucky student gets a few bonus points for finishing grading. They keep taking these quizzes endlessly with some answers people know and one new answer that no one does. The teacher is the bank, the students are participants in the blockchain, the quizzes are blocks, the questions that everyone knows are transactions that can be checked for validity, the answer that no one knows is the proof of work solution that must be produced (proof of stake would be like a rock paper scissors tournament among the students with already good grades to determine whose grading skills should be trusted), and the wall at the back of the class is launched into outer space travelling away at the speed of light so no one can get to it without breaking the laws of physics.