One major aspect of Einstein's theory of relativity is known as time dilation. Time dilation establishes that when something is going near the speed of light, or when near immense gravity, time slows down for that object compared to outside objects. This happens because the speed of light is always constant, no matter what. In order for an object in the presence of strong gravity, where light is bent, to record the same speed of light as an object in normal gravity, time must slow down for the first object. Near black holes, time slows down for objects descending into the black hole. As you fell into a black hole, outside observers would see you slow down as you approached it and eventually freeze altogether at the event horizon. Due to the high gravity, time dilation makes you appear as slowing down, and the event horizon light cannot escape, so an outside observer cannot view you past this point. Do to the time dilation that you are experiencing, you would view the Universe in fast forward, as the light from the Universe warps in the gravity and reaches your eyes in the black hole. As you reach the center of the black hole, the singularity, space, and time are infinitely distorted. At this point, space and time essentially switch places. Normally, one can choose where they move in three-dimensional space, while time marches forward without our control. In a black hole, space is one dimensional due to gravitational distortion- you can move only toward the singularity. While most think that meeting the singularity is the only possible future at this point, some theorists speculate that since space and time have swapped places, you would now be able to choose where to move in time, resulting in possible time travel.
All of this information is purely speculation. No scientist has ever been anywhere near a black hole, and there is no experimental evidence for this theory. The event horizon is called so because we can never witness an event inside. As exciting as it is to imagine, we will never be able to see inside a black hole and have no way of confirming the many theories on what would happen if we could. Additionally, anything going into the black hole is either incinerated by the hot dust surrounding it or ripped apart by the high gravity. Trying to figure out what would happen if the object wasn't destroyed is useless because there are many ways the object would be destroyed long before any warping of spacetime allowed for time travel or reaching the singularity.
[P1] When near huge gravity, time slows down. [P2] An outside observer watching something fall into a black hole would watch it slow down and freeze. [P3] For an object entering a black hole, space and time are warped. [P4] The warping of spacetime would lead to an inescapable movement toward the singularity, but a potential choice of whether to travel forward or backward in time.
Rejecting the premises
[Rejecting P1] This is due to the theory of relativity, which is a flawed theory.