The idea in the story of the jeweled Stupa that Śākyamuni Buddha creates a unified world out of many worlds is especially significant. The Lotus Sutra is an integrative sutra. Throughout, it emphasizes unity, oneness, integration, some kind of coming together. As the truth is ultimately one, i.e., without internal contradiction, so too the teachings of the Buddha who discovered the truth must be one. That is, finally there can be only one Buddha-way. But in the Lotus Sutra, the one does not destroy or denigrate the many. Though integrated, though the many become as one, they remain many. The cosmos only exists by virtue of the fact that it has worlds. Similarly, in the Lotus Sutra, the teaching, the Buddha Dharma, only exists by virtue of the many teachings. Neither right views nor right living can be a matter of replacing the many by the one.

That the one who creates a single world out of many worlds is Śākyamuni Buddha is related to his being, as said earlier, both one and distributed throughout the cosmos. In other words, Śākyamuni Buddha can unify Buddhism and the cosmos, and therefore the life of the true hearer precisely because he himself is both one and many.
A Buddhist Kaleidoscope; Gene Reeves, The Lotus Sutra as Radically World-affirming, Page 182