Oooh I dont want proof specifically -- I 'm just discussing this.
Proof points, before a case is filed, have to be very strong and with supportable evidences given...
Firstly you need to prove ownership -- with what you have there is all circumstantial with no "proper protections" validating claims.
Secondly that probably wouldnt get filed properly and end up in some minor "Arbitration court" as it would be just one persons word against another.
In order to properly validate a claim anyone wishing to copyright their work, giving it the "proper protections", would seek good practitioners in that field of work - Not disclose it before filing, otherwise you place it in the public domain.
Those chosen to practition your "Prior art" would be required to sign non-disclosure agreements first - making a perfect audit trail of events, independent of yourself, validating your claim to ownership.
If your work has strong independent evidences those are proof points adding strength to claim of ownership.
Just saying you own it isnt enough --- date and time stamps using IT systems can be maliciously altered - no Attourney worth his "Silk" would base a case on that.
The world of IPR protection is complex.
It's the same if I was to invent something and I told you about it prior to filing a patent -- YOU could claim ownership of my idea.
Reason??? -- I placed it into the public domain before putting the "proper protections" in place.
hot yippidee dawg.