Why did the deity put the fossils there? In order to confuse us? In order to challenge the faithful? It defies reason. You can only put it as a mystery of faith. But it needn't be.
If you are going to create a planet (or universe) from scratch to be the home of an intelligent species, including a realistic history is critical to give that species sufficient historical context to learn about how things work.
Understanding evolution and biology is a lot harder if you have no fossil record. Understanding plate tectonics is a lot harder if you don't have a consitent geologix record. Understanding physics is a lot harder if you don't have a light coming in from events that predates the creation of the universe.
Thus if you grant that the universe was created 7000 years ago with a huge, detailed and consistent history, the clear implication to me is that we are intended to study that history to understand the universe in which we exist.
Went into a creationist museum once (real thing). And the literal answer to your question was ”Yes, Satan put the fossils there to temp us away”.
I can’t attribute that to all creationist, but it was the case for the few I interacted with.
He changed the subject and never brought it back up to me again.
In Heinleins “Book of Job,” this is suggested as the answer in one scene. A grand book