Why do text messages from others keep being resent?

It may be that the signal in the sender's place is not good and the text message cannot be sent, so the sender will continue to send the unsent text messages until the signal in the sender's place is better. It will be sent automatically and you will receive repeated text messages. However, it is not ruled out that some people use prank software to harass you, such as SMS bombers, etc., which can send you repeated text messages to harass you.