Well, there are black holes in the centers of galaxies including our own Now then, we know that matter can fall
Into black holes. But perhaps, by some mechanism yet to be elaborated, black holes are / we’re also “sources” of matter? ??
It could be, I suppose, that when a big enough black hole collapses, that it turns inside out and forms a gusher of matter/energy into a different space/time. We don’t notice that happening with “ordinary” black holes in our universe. Although we can’t see them directly, we can detect their enormous masses by the effects they have on nearby matter that we can see. But maybe a big enough black hole would do the inside-out trick, and the black hole’s mass would disappear from our universe. There is no evidence for this inside-out stuff, but it does solve the problem of how we got out of the biggest of black holes.
Another speculation some have resorted to is the idea that our universe is inside a black hole, so nothing actually got out in the Big Bang.