I have a timestamp showing the unmodified file! Will you accept my late work?

No. It’s not a question of me believing you or not. I’ve never been able to use timestamps on files. I keep on my laptop hard drive a text file “dated” to the date and time of the sinking of the Titanic (I mean the one from 1912, not 1997). Here is how I got it:

[jhemann:~] 14:55:29$ SetFile -d "04/15/1912 02:20:00" ~/SinkingOfTheTitanic.txt
[jhemann:~] 14:56:19$ stat ~/SinkingOfTheTitanic.txt
16777221 22202324 -rw-r--r-- 1 jhemann staff 0 49 "Sep 27 14:56:19 2021" "Apr 15 02:20:00 1912" "Sep 27 14:56:19 2021" "May 21 09:48:16 2048" 4096 8 0 /Users/jhemann/SinkingOfTheTitanic.txt

As you can see, timestamps are unreliable. At base, these are all mutable bits on machines over which we have full control. Of course our usual uniform amnesty for late work applies to you in this instance as well.