Mankind has come up with a plethora of ideas that can be grouped under the word “religious.” Druids, Greek gods, Islam... the fact that we have come up with a word under which to group them means nothing but that we have recognized that some things are merely imagination in the service of justifying behavior.
And now you claim that "religions" is a word used to group ideas which are merely made up in the service of justifying behaviour.
Huh.
To boomerang the classic atheist argument against the existence of God, (if morality exists God adds nothing to it, and can be eliminated by Occam's razor) --
Why then should religion have begun, (or, for that matter, persist) if animals show these behaviours already without resorting to *anything* to justify them? (Whence the need to justify what is by your accounting instinctive? And -- probing deeper -- why would anything need "justifying"? Where did the concept of justifying come from in the first place? Humans are animals, right?
Quit contradicting yourself.
Cheers!