I think you might need to read a book on the subject

the creators were fully aware they were creating a weapon of genocide and mass destruction and were hyped up about making it huge. even the test explosion killed locals through radiation. “oh i didn’t know someone was really gonna use this on civilians” is quite a dumb excuse.

They were fully aware they were making a device to stop Nazism and tyranny and win the war. Heroes, the lot of them.