Does time only exist in the human mind?
See this car, it is rusting.
Rust is an oxidation reaction. It happens at a certain rate. Whether or not a human being looks at or thinks about this car, it will be more rusted in a year than it is now, and the degree of change over time is predictable.
See this image of merging galaxies. They are 3 billion light years away. The light that allows Hubble to see them has been traveling towards us since long before humans existed. If time does not exist without humans, then light could not travel, since travel requires time.
A seed cannot fall from a tree without time. The sun cannot rise in the morning without time. It cannot rain without time. Those three things would still happen if humans didn't exist. Because, if they didn't, we wouldn't have any oil to put in our cars.
If time came into being when a human first thought about it, how did the human species evolve to that point without an elapsing of time? How did an asteroid hit the Earth causing an extinction of dinosaurs if time was not elapsing? How did the Earth cool enough for life to form on it, without time elapsing?
If something that takes time to happen, happens, without the contribution of the human mind, then time must exist outside of the human mind.
Space and time are interconnected. They were interconnected before humans existed and they will be interconnected after humans are gone.