Here Jerusalem is created as a place of rejoicing and a place of joy. Jerusalem has never been that in history, but it will then be known as Zion, the spiritual capital of the world.
The reason Isaiah put those times of death is because they are probably symbolic or typical. Death is not the same in this new earth or what we know in Hebrews as the world to come. In one place in Isaiah it means life would be like the life of a tree. When four wheeling on the mountains of Colorado we saw some little trees which we were told were from the beginning of time.
If they live the way they ought there should be no curse for sin in this glorious place known as the world to come. God answers before they call and hears while they are speaking.
There is also change in animal life in this earth. Now certain animals kill others for food. In this kind of earth there will be no ravenous animals.
According to Revelation 19:14 we will be coming back to reign with Christ on this new earth. I can’t go any further about our part in this. I do know that we must accept Christ or we will not have a part in this.