What if time does not even exist?

I have a question that I always ask myself: what if I am living my present now, but my sister, for example, is living her present in my future.

In other words, my consciousness and my present are here now, and my sister's consciousness and present are in the future. And other people are still in both the past and the future.

For example, at this exact moment Leonardo da Vinci is alive, but in his reality and in his present. But for me now he is already dead. What if there is no such thing as future and past? What if it is all one thing. What if time does not even exist and what really exists is my consciousness?