Causality in thinking or external to us

So what do we see if not certain entities (=ideas)? After all, it is an entity behind, isn't it?

I will try to explain briefly and figuratively, the claim is very simple, since it is not possible to see a causal relationship, but only a temporary change. So even if we observe an entity that describes a causal relationship (say an idea), we still have to assume that there is a causal relationship between this entity and the phenomena in the world. And if so, it apparently did not help at all.

For example, what is the similarity, if we could display the Platonic ideas on our cell phone. And for example, a “causal relationship” would be displayed by the flashing of a red screen on the phone to describe it.
And so when we see two balls colliding, we get a red flicker. And when we see the piece of wood that burns in the fire, we get another red flicker. We still assume that the collision of the balls is what caused the flicker. But where does this come from? Just because of a temporary relationship.. So what good were the ideas flashing before our minds' eyes?

It is not about an entity but about a relationship between events. When you see the speed of a body, you see the body and that it has speed (that it is moving). Is its motion an entity? This is how you see a causal relationship between two events.

I didn't understand, but finally, with a materialistic view of reality as you say, you can't derive the concept of causation from reality. So if you assume that it exists, how can you see it with the eyes of the mind? If there is no dimension that the eyes of the mind can see... you must at least assume that there is an additional dimension to reality. Otherwise, why do you need to use this concept? And anyway, this dimension contains entities, and they are the ideas, right?

Speed is really a definition of change in position per unit of time, and this can be perceived with the eyes along with thinking. But a causal relationship cannot be given as a given. No?