That does not say "MANY but not ALL". That is only your assumption. The English word "many" is translated from the Hebrew word "rab" there which does not mean "many but not all". It simply refers to a large number which may or may not refer to all of something.
Here's a couple examples where the word was used to refer to all of something rather than many, but not all of something.
Genesis 21:33 And Abraham planted a grove in Beersheba, and called there on the name of the Lord, the everlasting God. 34 And Abraham sojourned in the Philistines' land many (rab) days.
Is this referring to many but not all of the days Abraham sojourned in the Philistines' land or to all of the days he sojourned there of which there were "many"? The latter, right? Clearly.
Genesis 37:31 And they took Joseph's coat, and killed a kid of the goats, and dipped the coat in the blood; 32 And they sent the coat of many colours, and they brought it to their father; and said, This have we found: know now whether it be thy son's coat or no. 33 And he knew it, and said, It is my son's coat; an evil beast hath devoured him; Joseph is without doubt rent in pieces. 34 And Jacob rent his clothes, and put sackcloth upon his loins, and mourned for his son many (rab) days.
This is referring to when Jacob thought his son Joseph had died and he then "mourned for his son many days". Is that referring to many but not all of the days that Jacob mourned or is it referring to all of the days he mourned, of which there were many? The latter, right? Clearly.
There are other examples like these where the Hebrew word "rab" did not mean many but not all as you believe is the case in Daniel 12:2, but instead refer to all of something with the number of all of something being many.
It's clear to me that Daniel 12:2 refers to the same resurrection of all of the dead that Jesus referred to here:
John 5:28 Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice, 29 And shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation.
And what about the reference to those who rise "to shame and everlasting contempt" in Daniel 12:2? Did you miss that?