Do we exist within the tip the horn of a giant rainbow unicorn?
The question is exactly as pointless. It is not the way science works. It is pointless to enunciate a pure speculation, and ask if by any chance that speculation happens to be true.
Because it is impossible to prove that it is not. Any speculation could be "true".
And for this reason, it is not the way science works. Science is not about validation or invalidation of speculation that could be true.
In other words: it is your job to tell us why do you think it is. And then, and only then, science could try to understand if
1) that hypothesis do not contradict with observations
2) it is as efficient as other model to describe observations
3) it is more parcimonious (it explains as much, while assuming less)
Note that nowhere I listed "it is true". Science is not about theories that are true or false. There is not way to know what is true anyway. A theory is good or not. Not true or not. It is good if it describes lot of observations with few hypothesis.
So your speculation, as mine with unicorns, as any, could be true. But that is not the point. The point is: what observations can be explained, or at least explained more easily, with this "theory" (which will gain its status of "theory" only when you'll have proved that it checks the criteria I listed: parcimony, coherence, ...)