Simply not true. And the falsity of this claim can be known by acknowledging the myriad inter-subjective experiences we can all have, and cannot deny, regardless our use of "imagination." For example, the effects of gravity on your body. Would you claim that there are those out there who can make gravity a subjective experience, and can use their imagination to overcome it, or cancel it entirely?
I will agree that we only really get an interpretation of what is truly "real," because such experience is inevitably filtered through our own, individual sensory perceptions. However, all reliable/testable/demonstrable evidence points to the underlying "reality" being the same for all of us, without the insane amounts of deviation we should expect under your assumptions.