5:9 And they sang a new song, saying,

"Worthy art Thou to take the book, and to break its seals; for Thou wast slain, and didst purchase for God with Thy blood men from every tribe and tongue and people and nation."

And they (the 28) sang a NEW SONG saying,
"WORTHY ART THOU to take the book and to break ITS SEALS;

Remember that the inheritance scroll could only be opened by the owner when payment/redemption was made.

Let's personalize this:

WHAT was bought? you and me (men)
HOW was this price paid? with Jesus Christ's Blood
WHO received it? God, Jesus Christ's Father

This new song clearly results in OUR redemption!