I found this in a book cafe and thought it might be appreciated here. 漢字字形史 goes over roughly 700 characters and their history. As you can see from the diagram, it shows how some characters have common descendants. I think that’s pretty cool.
I was just thinking the same. Wiktionary suggests “This character, 仮, is a variant form of 假.” which has a different etymological origin, so perhaps the final form was inspired by the above flow, but didn’t actually directly come from it. Perhaps the book itself may have something to suggest elsewhere.