Question about the Hypothesis of our Universe beeing in a gigantic Black hole

So i recently had a short chat with someone Who did an AMA about a physics related topic, now it opened a few questions up for me. Its all based on the hypothesis that we are in a black hole. Now given the Massive size etc its effects would be that spacetime became what we know it is, it flattens spacetime and causing it to be linear rather than having everything happen all at once everywhere. Now based on this I thought it'd explain why spacetime behaves as it does in the sense if we pump enough energy into an object (Mass, heat, gravity or whatever) it'd counteract the forces generated by this supermassive black hole, allthough on a minimal scale from its perspective, it does cause time to become relative on our scale.

Is this a valid thought process or am i spewing garbage?