‘I Jesus have sent my angel to testify these things to you for the churches.'
Compare Revelation 1:1; Revelation 22:6. This statement stresses that the churches are directly involved in all that is written. They need to know them because they are revealed for their benefit as those who must go through them. It is a personal message from Him to them through His special messenger, His angel.
‘I am the root and the offspring of David, the bright and morning star.'
Compare Revelation 5:5; Revelation 2:28. Christ applies to Himself the Old Testament promises in respect of the coming one. He is the promised son of David (Numbers 24:17; Isaiah 9:6; Isaiah 12:1,10). See also on Revelation 2:28. He is the bright and morning star, the welcomer of the new day (Numbers 24:17). The bright and morning star is an appropriate description with which to end. The night is passing and it is then that the bright and glorious morning star appears. These citations of the Old Testament stress that the One revealed cannot be distinguished from the One promised in the Old Testament. He is the fulfilment of the Old and the New.
Note how this statement of His Davidic descent is in close proximity with His statement that He is the Alpha and the Omega, the beginning and the end (Revelation 22:13). Compare Romans 1:3-4; Mark 12:35-37.