Question 1: Are humans somehow above Angels?
Psalm 8 is very clear - Man is lower than Angel.
4 what is mankind that you are mindful of them,
human beings that you care for them?
5 You have made them a little lower than the angels
and crowned them with glory and honor.
Philippians 2 is clear that this debasement was part of God's plan:
In your relationships with one another, have the same mindset as Christ Jesus:
6 Who, being in very nature God,
did not consider equality with God something to be used to his own advantage;
7 rather, he made himself nothing
by taking the very nature of a servant,
being made in human likeness.
8 And being found in appearance as a man,
he humbled himself
by becoming obedient to death—
even death on a cross!
Therefore God exalted him to the highest place
and gave him the name that is above every name,
10 that at the name of Jesus every knee should bow,
in heaven and on earth and under the earth,
11 and every tongue acknowledge that Jesus Christ is Lord,
to the glory of God the Father
The thing you are adding - that somehow Jesus' incarnation is applicable to all humanity is the part that makes no sense. The burden would be on you to prove that.
Finally, Jesus' did not "mix" the natures - Traditionally the hypostatic union says he was fully God and fully man - but there is never a suggestion that the two natures were combined into one essence.
Question 2: Ministering to Fallen Angels
As to Jesus becoming an Angel - he didn't need to. The closest one could come to understanding this would be in 1 Peter 3:19 20:
For Christ also suffered once for sins, the righteous for the unrighteous, to bring you to God. He was put to death in the body but made alive in the Spirit. 19 After being made alive,[d] he went and made proclamation to the imprisoned spirits— 20 to those who were disobedient long ago when God waited patiently in the days of Noah while the ark was being built.
Some view this as Christ preaching to the Angels - but there is never a suggestion that Angels need atonement. This isn't to say they are perfect, nor that they aren't fallen, but we just have no biblical information about this.