@Paul Muad'Dib...
At first I was not certain if you are serious about your claims or just Trolling like me but here goes...
A long time ago in a galaxy far far away I knew someone important (a brotha) at Warner in their video game making department!
We would see each other at a friend of my younger brother's home usually for fights like Mayweather and other payperview events!
We got into a discussion about comics and eventually exposed that most executives at DC really didn't frequent comic shops let alone Comic-con but were failing badly in their video game making projects!
At some point he petitioned me to right a treatment to see if I could help them out which I did and presented him something he literally enjoyed while we watched yet another Mayweather victory that he missed focused squarely on my little script!
I didn't here from him for a while until I got a delivery "officially" from their department of the duffle bag I loaned him of various graphic novels I owned to help acclimate him... I'm talking Death of Superman, Tower of Babel, Crisis on Infinite Earth, etc. etc
I later joked about the "official" delivery where he could have just handed them back to me or gave them to my brother but whatevah...
Legalities in this business are no joke as lawsuits are a dime a dozen but most companies steer clear of potential entanglements whenever possible!
Now what was my original idea?
It was something where The Joker had seven deadly jokes one for each Justice League member that took them through trials and tribulations at a comedy club!
Later... Batman: Arkham Asylum comes out and Joker is wilding out similar to what I wrote considering that super hero games really sucked back then and sure I noticed some similarities but just like Heath Ledger's Joker or Joaquin Phoenix that's all they are!
Note: Rocksteady made 3 out of the 4 Arkham games where Origins was WB in house
I don't own Joker or any of DC's catalog and I never officially worked for them anymore than you have writing Black Panther!
In this super hero genre there are all types of "shiny" things and primary colored spandex and oh so random mcguffins so what can you really claim as yours!
Can James Earl Jones even claim co-creation of Darth Vader with George Lucas simply because his voice is synonymous with the character... That's a slippery legal slope which could have all actors, writers and creators replaced by robots!
You could design magical gauntlets, floating buccaneer boots and teleporting earrings for Black Panther but claiming creative licensing over a character that you did not create in the first place is putting you in this territory...
https://blackexcellence.com/sophia-stewart/
Plus... You would have to show that very busy professionals even came across your work and would risk their careers stealing from you as if they did not have enough qualifications to get hired in the first place!
Then you have to also contend with the fact that both Marvel and DC own the rights to the words "Super Hero" since they furthered the concept long before you and I were born!
Someone could accuse you of taking their ideas if they have things that you depict presented years before you picked up a drawing pen!
Just copyright your own characters and stay creative... Work for hire means work for hire!
Peace