The Universe's Existence is Explicable

For this discussion, I will be claiming that it is at least more plausible to think the universe's existence has an explanation than its negation. So, without further ado, here's my argument: 1. A proposition is plausible if it has explanatory power.2. If an inexplicable proposition has no explanatory power, then it is not plausible.3. Inexplicable propositions do not have explanatory power.4. Therefore, it is not plausible to posit inexplicable propositions. For a proposition to have explanatory power in a plausible sense, it needs to explain why something exists through probability, reason, or observation. There are two kinds of explanations; either something is necessary by its own nature or it requires an external reason for its existence. Inexplicable propositions, on the other hand, are propositions that are said to simply be the case without any reason for why they are the case. These inexplicable propositions may possibly explain other facts, but this could apply to many other competing inexplicable propositions as well. For example, the fact that I have presents under my tree could be said to have appeared without any reason. Or perhaps Santa Claus popped into existence for a moment to deliver the presents but then vanished into non-existence for no reason. Both of these would trivially explain the fact that I have presents but I would have no reason for positing either of them to be true. On the other hand, I do have valid reason to think that my parents or family put the presents under the tree through observation. Now, which one would you say is more plausible? I don't think it is difficult to understand that explicability should be the default position. Even if I did not observe who provided the gifts, it seems more plausible to think that it is explicable (regardless of whether we know what that explanation is) than to arbitrarily posit inexplicable propositions that have no reason for why we should think them to be true. What this suggests is that in order for someone to claim that an inexplicable proposition is true, you'd need to provide a reason why it is implausible or impossible for the universe to have an explanation. However, doing so would subject you to assuming premise (1) as true because you'd be providing an explanatory reason for positing an inexplicable fact. The universe in particular is known to exist because we have reason to think it does but to then propose that "it exists because it exists" just seems to be a useless tautology. It does not answer why the universe exists at all but instead begs the question. Even if the universe is eternal, that would still not answer "why" it exists. Let me just distinguish here between having a reason to think that something exists and knowing why that thing exists. These two should not be confused, even if they are related. The former has to do with existence and the other has to do with causes. Perhaps the universe must exist or was caused to exist eternally/temporally. Both of these options qualify the quality or kind of existence in question. Logic would be an example of something that must be true because it cannot be false. On the other hand, a computer exists because it was created by humans, not because it has to exist by its nature. It may be argued that we cannot know what the cause of the universe is because it is beyond our scientific observation. This is not true as we can still infer or deduce a cause through reason. However, even if I was to grant this assumption, this only shows that we cannot know what the cause is. It does not tell us that it is implausible or impossible to think that it has some kind of cause. I hope that this was clear enough. Looking forward to your objections!