Here comes another Riley!
My infix is who you are
My prefix is my infix's alpha
My suffix is a short little insect
And me you shall not dissect!
I think the answer is
Adamant
My infix is who you are
Man - General word to represent a human being.
Original answer Am - First person singular of the verb to be, e.g, "I am".
My prefix is my infix's alpha
Adam - from the Bible, first man (alpha male) created by God.
My suffix is a short little insect
Ant
And me you shall not dissect!
Adamant - a legendary rock or mineral (think of Wolverine's adamantium).
Title
The author appears to be adamant in their assertion. Also, adamant translates from Greek via Latin as "not to be tamed" which could tie in with the wording of the title