Vlad,
The moment you suggest a composite you are no longer talking about a necessity, since the components are entities in their own right and the combination is dependent on the components having no independent existence apart from them.
Why are you persisting with this gibberish, and why are you still running away from justifying the “necessary” part of your assertion about a cause? An infinite universe that's its own explanation could also have developed any number of discrete parts over the millennia. So what?
Yet again: it’s YOUR claim that the universe must be contingent on a cause other than itself (which you then special plead into not needing a cause of its own). It’s YOUR job there to justify YOUR assertion. The moment you collapse into the fallacy of composition – ie, “the universe has lots of bits that are contingent on other bits, therefore the universe itself must be contingent on something other than itself” – which is all you have so far, you abandon even the pretence of a justification.
Without more fucking around with more “but the universe is made of parts” irrelevance, why not finally try at least to answer this basic question?
If the fallacy of composition isn’t all you have, what’s stopping you?