In considering this passage, it’s important to recognize that “firstborn” doesn’t necessarily mean “born first.” Instead, firstborn can refer to priority in time, or supremacy in rank. (1) In Jesus’ case, both are true: as God, Jesus is before any created thing, and as God, Jesus is greater than any created thing. Thus, Jesus has a position of authority and superiority over everything. Firstborn “…of the dead” simply refers to His resurrection as a herald of things to come for God’s people.
Some of Jesus’ disciples had a similar experience when a cloud overshadowed Peter, James, and John while they were together with Him on the Mount of Transfiguration (Mark 9:2-8). That was the place where the voice of God spoke to them from the cloud, saying, “This is my Son, whom I love. Listen to him!” (Mark 9:7 NIV).
While clouds often tend to obscure our view, the Biblical presence of these clouds serve to reflect or illuminate God’s power and glory. Thus, we should not be surprised to learn, “…He is coming with clouds, and every eye will see Him.”
(1) See discussion of prototokos from Colossians 1:15, the same word translated “firstborn” here in Revelation 1:5: Constable, Thomas. DD. Colossians. (n.d.). https://soniclight.com/tcon/notes/html/colossians/colossians.htm [1:15b]