Time is a measure of gradual change from the past to the present to the future. Past, present and future exist where there is someone or something to physically observe the events. Hence the existence of time truly makes sense where there is an observer.
In our physical universe, we can easily conclude that time exists. (Obviously, I am not talking about the hours, minutes and seconds that a clock represents. That is something totally different- a man-made system to measure time.) We are constantly observing the flow of events from our past to our present to our future. We analyse, become judgemental and make predictions.