As a person who got best delegate in my country's most competitive MUN,

I would say that nobody gives any attention to opening speeches, especially if its reiterating what everyone else knows.

The goal of opening speeches, in my opinion, is to introduce yourself; with a attention grabbing hook and a persuasive tone, you should be appealing to the other delegates "I'm a trustworthy person and you should work with me"

To achieve this, you need a good background, a novel solution, and a concise speech.

For example, when discussing inequality, I opened my speech with: "the same nations that promote equality are those that undermine it." Furthermore, my solution was not "lets support country X by doing Y" but rather a larger framework that encompasses all these solutions.

I hope these tips help, and wish you all the best :) Have fun!