yes this really helped and thank you.
but I would like you to hear me out.
it is proved that they can bring back dead people to keep them on the isl, so I dont think he can be dead, although he can be hiding or forgotten.
I did some research and if we lure out the animals and the ones that doesnt fit, we only have left acouple of villains, which we never even heerd of in the movies or the novels. so, his father can also be a villain that is forgot. that gives us the second option.
my other opinion is he could have escaped the isle. well, everything originally started out when carlos tore a hole in the arrier right? but if I'm recalling correctly, nobody in aroudon knew about this hole, feel free to correct me. this proves that the barrier can be tore down. this gives us two more options. eithert a villain that escaped or hero got away.
we have 4 logical explanations right now. however, I don't think his father is forgotten. somebodyhas to know about it and I'm pretty sure carlos went toanyone who could know the smallest thing about his dad. this gives us that his dad may be dedlike you said (low posibilty) or people are asshamed of him. that gives us my final conclusions. I don't think it was a villain since people would have gone after him instead of forgetting so if lure that out, we are left with either dead or a hero.
I also hope he learns more about his dad and I would be glad if you could answer since every answer is taking us closer to an answer.