They do not tell you what the marks meant to the person who made them, what the marks communicated to subsequent visitors, or whether subsequent visitors could or did read them.

The footprints tell you that someone walked through that passage.

They do not tell you whether that person was afraid, excited, bored, spiritually engaged, or simply focused on the practical task at hand.

This is not a failure of the archaeological methods or a gap that better technology will eventually fill.

It is the fundamental limit of material evidence as a window into human experience.

Physical objects and marks record that something happened and sometimes how it happened.