You haven't read Daniel 7 it seems. Daniel 7:13 is the proof text for the Son of man not being the Ancient of days.
Verse 18,22,27 says, in the KJV says that the kingdom, power, and authority belongs to the people. This means that since the son of man posses the same thing as the saints of the Most High, the the son of man himself is one of the power, one of the saints, not the Ancient of days or God Himself. Daniel 7 is a mighty chapter against the deity of Jesus.
Daniel 7
18But
the saints of the most High shall take the kingdom, and possess the kingdom for ever, even for ever and ever.
...
22Until the Ancient of days came, and
judgment was given to the saints of the most High; and the time came that the saints possessed the kingdom.
...
27And
the kingdom and dominion, and the greatness of the kingdom under the whole heaven, shall be given to the people of the saints of the most High, whose kingdom
is an everlasting kingdom, and all dominions shall serve and obey him.