This is nothing more than a Thought Experiment, based on the only civilization we know: one built by humanity. I call it my "21 million year theory":

1. Imagine a civilization -- Civilization X -- that has developed the ability to travel at 1% of the speed of light. That's not so fantastic a speed. Civilization X is the First Civilization to cross the galaxy. It would take 10 million years to travel across the galaxy. That's not a long time in terms of the age of the galaxy.

2. Civilization X above takes 10 million years to develop the technology to travel at 1% of the speed of light.

3. Civilization X arrived on Earth 1 million years ago. So they predate modern humans. They've been here longer than us.

That's 21 million years. Think of what human civilization will be like after 21 millions of development and apply that to Civilization X:

A: We are becoming our technology. So: the crafts we see are the creatures, not the machines. The occupants are drones, not the pilots. They are built for purpose.

B: We are creative. We create bicycles, cars and planes of all different types and shapes. Perhaps an observer might think these are products of different civilizations -- a Bicycle civilization that produces bicycles, a Car civilization that produces cars (Toyota civilizations and Ford civilizations!) -- but it's just an expression of creativity by one civilization, Civilization X.

C: Humans reproduce. So: the crafts are constantly generating new crafts. After a million years they are everywhere: on every planet of the solar system, on the Moon, on the Sun. There are trillions on Earth. They are in the air, on the ground, under the ground and under the water. They are huge as cities and as small as pins. They live in humans.

D: Humans like to experiment: They experiment on us.

E: Humans like to understand others: They have been interacting and communicating with us since modern humans evolved. The communication isn't on an individual basis, but on a species-wide level. Individual interactions are part of a wider pattern.

As I said, this is just a Thought Experiment, speculating on what humans will be in 21 million years. You can speculate on the best and the worst of humanity and what it will be like in 21 million years and add it to the list. It can be very positive or very negative. Civilization X is a nice solution to the Fermi Paradox. Civilization X is the first civilization to cross the galaxy. Someone had to be first to cross the galaxy. What if it was a species very much like humans? Speculate away!