The only minimum thing we can be sure of is our own conscious, it would be very strange if this was the only truth. We may become sure of the truth of reality only when we get ourselves to somehow develop a device to test the consciousness of other beings, but then again, it might happen it’s part of just the imagination. I believe if we solve the hard problem of consciousness we’ll grow as a civilization as a notch. One possibility to approach the credibility of true reality is to rely on scientific conclusions and believe everything has an explanation. And yeah all these matter, since reality shapes us.