Here are the problems with your model.
When an object or observer reaches a black hole’s event horizon and passes through it is curtains and can never reemerge.
This can be explained with a Minkowski space-time diagram.
The observer’s present time and location is where the observer’s past and future light cones meet.
The region inside the past light cone is where events have occurred in the observer’s past and events which will happen in the observer’s future fall inside the future light cone.
As the observer approaches the event horizon the light cones narrow due to gravitational time dilation and when it passes inside the event horizon at r = rₛ the time like and distance like terms in the Schwarzschild metric are interchanged.
Geometrically the light cones “tip over” and the singularity is in the observer’s future light cone and the event horizon is in the observer’s past light cone.
To travel back towards the event horizon requires the observer to travel back into his past which needless to say is impossible.
This eliminates the idea of the universe existing inside the event horizon of a giant black hole as your matter is ejected outwards to the event horizon and therefore into the past.
The other issues with your model is when we observe matter ejected from supermassive black holes in the form of quasars and galaxies with active galactic nuclei (AGN) an accretion disk is necessary.
As the material from the accretion disk approaches the event horizon it is heated up to millions of degrees K due to friction and the conversion of gravitational potential energy into heat.
Matter is ionized along with the creation of X-ray and gamma ray photons.
Ionized matter can have sufficient kinetic energy to never reach the event horizon and is ejected as jets the dimensions of which depend on the thickness of the accretion disk.
Since the ejected matter travels through space time it is subject to the laws of special relativity where it cannot exceed the speed of light.
Yet galaxies with redshifts exceeding z = 1.46 have recession velocities exceeding the speed of light and therefore are not ejected through space-time.
Instead galaxies are being carried along by space-time expansion known as the Hubble flow where the speed of light is not an upper limit.