Life, death, the present, the future as human beings, all this is certain, although there are theories and facts for everything, as you say we are human beings, the only ones capable of understanding all this, you have many questions and I also, there are many answers but the truth we do not know what it is in reality, your cat is in his world very different from ours and he has no questions only live day to day while we even wonder what will happen tomorrow? it's a very complex issue I hope you have good answers to so many questions